Editing Warhammer 40,000/9th Edition Tactics (section)

==Playing the Game==

Before we get started, note that 9th edition has GW releasing updates to Matched Play in yearly supplements titled "War Zone: [x]" While the core rules for this edition is practically the same, each War Zone supplement changes the game slightly. That is, until 2022, when War Zone Nephilim came out and [[Skub|created a rational, reasonable discussion]] within the community after it cut your CP pool in half, made all WTs and Relics cost command points, and revamped secondaries. Luckily, no one ''says'' you've gotta play Nephilim if you and your group doesn't want to.

[https://www.warhammer-community.com/wp-content/uploads/2020/07/Lw4o3USx1R8sU7cQ.pdf The basic rules of the game are available here.]

===Secondary Objectives (AKA: Prioritizing Your Targets)===
New to 9E is the addition of secondary objectives...okay, not entirely. Unlike Maelstrom of War's cards, these are always active (although you can only get 15 VP per secondary objective), but you can only pick one from each category (listed below). Some missions even give you special secondary objectives to pick up if you want something better-tailored.

Some of these objectives give units actions - be careful as these have specific criteria that might mess with your gameplan. Also, just having your whole army painted grants a free 10 VP at the end of the battle: nobody's asking you to make them look like Golden Daemon winners, but just make sure that other people can look at them [[THIN YOUR PAINTS|without hurting themselves]]. 

As previously mentioned, these Secondaries have gone through quite a few changes since they first came out. For example, each faction has their own specific secondaries and you're no longer limited by the number of faction secondaries you can take, just by category. Nephilim removed lots of the situational secondaries (like Titan Slayer or Slay the Warlord that only gave you 8 or so points), making them more generalized so that you could keep scoring them throughout the game. On the other hand, it also removed Domination/Stranglehold, which was the one that piggybacked on the Primary (essentially doubling your VP). 


<tabs>
<tab name="Purge the Enemy">
*''Assassinate'': 3 VP for each {{W40kKeyword|Character}} you kill, 1 VP if you kill the Warlord. In Nephilim, this is also your default Purge Objective, but can be switched.
*''Bring it Down'': 1 VP for any {{W40kKeyword|Monster}} or {{W40kKeyword|Vehicle}} you kill with 9 or less wounds, 2 VP for each enemy {{W40kKeyword|Monster}} or {{W40kKeyword|Vehicle}} with a Wounds characteristic of between 10-14 that is destroyed, and 3 VP for each enemy  {{W40kKeyword|Monster}} or {{W40kKeyword|Vehicle}} with a Wounds characteristic of 15-19, and 4 VP for 20 or more.
*''Titan Slayers''<sup>[Removed in Nephilim]</sup>: 10 VP if you kill one {{W40kKeyword|Titanic}} model, but you max out at 15 if you kill more than one.
*''Cut off the head''<sup>[Removed in Nephilim]</sup>: The old ''Slay the Warlord''. The sooner you kill the warlord, the more points you get, so you better move fast. Also, be careful with resurrecting units, the one death that counts is the last.
***13 VP for killing it 1st round
***10 VP for killing it 2nd round
***6 VP for killing it 3rd round
***3 VP for killing it 4th round
***1 VP for killing it 5th round
</tab>

<tab name="No Mercy, No Respite">
*''Grind Them Down'': The Default for No Mercy, No Respite. Score 3 VP at the end of the round if more enemy units were destroyed than friendlies. 
*''Take No Prisoners'': If you select this objective, keep a Kill Points tally. Each time an enemy model is destroyed (excluding VEHICLE, MONSTER or CHARACTER models), add a number of marks to this tally equal to the Wounds characteristic of the destroyed model. At the end of the battle, divide your Kill Points tally by 10 and round down - the result is the number of victory points you score. In addition, if your Kill Points tally is between 50 and 99, you score 1 additional victory point, and if your tally is 100 or more, you score 2 additional victory points.
*''While We Stand, We Fight''<sup>[Removed in Nephilim]</sup>: Select the three most expensive <s>models</s> '''UNITS''' in your army. <s>Yes, models, we are counting all the wargear options. For each of these models that remains at the end of the game, you earn 5 VP.</s> Not anymore, as of the 2021FAQ these now specify "units" rather than models, making it absolute garbage. 
*''First Strike''<sup>[Removed in Nephilim]</sup>: 5 VP if you kill an enemy unit during the first turn, adding 3 more VP if you kill more enemy units than they kill your units during the first round.
</tab>

<tab name="Battlefield Supremacy">
*''Behind Enemy Lines:'' The Default Supremacy objective in Nephilim. Score 2 VP if one unit from your army, excluding Aircraft, is wholly within your opponent's deployment zone. Score 4 instead if two or more units are within the enemy's deployment zone.
*''Engage on All Fronts'': Score 2 VP if you have units totally within 3 table quarters and more than 6" away from the center of the board. You instead get 3 VP if you have units totally within each quarter and more than 6" away from the center of the table.
**Tweaked quite a few times to exclude units with less than x amount of models so check whatever book you're using for the exact wording: In Nephilim, you must be 6" away from another ''table quarter'', and a unit must have ''started'' with more than 3 models in their unit, or be a VEHICLE/MONSTER (but not Aircraft) to qualify. Which means that even if your bike squad has been reduced to the Sergeant, you can still score if he gets 6" away from another table quarter.
*''Linebreaker''<sup>[Removed in Nephilim]</sup>: 6 VP at the turn's end if you get 2+ units (excluding {{W40kKeyword|Aircraft}}) in the enemy deployment zone. Another classic.
*''Total Domination''<sup>[Removed in Nephilim]</sup>: 3 VP if you own more than half the board's objectives.
**This Secondary has seen lots of changes, before finally being removed in Nephilim because everyone tended to just double-dip on the objective game. 
*''Retrieve Nachmund/Nephilim Data''*: A Tally Objective. An Infantry or Biker unit wholly within a table quarter and 6" away from another table quarter can attempt to retrieve a servo skull. Roll a D6, subtracting 1 from the roll if it's being performed by a Troops unit. If the roll is less than or equal to the number of models in that unit, the action completes at the end of your turn, adding one to your tally.
**If performed twice, you gain 4 points. Three times, 8 points. Four times for 12. 
**Some actions, like Raise Banners, can be done by multiple units. Retrieve Data can only be done once per turn, so you're looking at a four turn investment for 12 VP max. 
</tab>

<tab name="Shadow Operations">
*A lot of the secondaries in this section were baked into the mission-specific '''Primaries''' in Nephilim. 
*''Raise the Banners High'': Your {{W40kKeyword|Infantry}} units gain a new action each turn in an attempt to emulate [[Dawn of War]]. When they move next to an objective, they can choose to plant a flag (action begins at the end of your movement phase), scoring you points so long as the objective remains in your control. At the end of every Command Phase and at the end of the game, you score 1 VP for each flag you have on an objective. Be sure to guard your objectives, as the enemy can immediately rip down your flags when they control your objectives.
**Super subtle changes, the important one being that the action can begin and succeed ''even if there are enemies around the objective,'' you just need to make sure you ''hold it'' by the start of your next command phase. That means that if you have a single Intercessor on it surrounded by 10 Death Guard Cultists (who aren't ObSec in DG), so long as the Intercessors don't do anything else, the action succeeds and you gain points.  
*''Investigate Sites''<sup>[Removed in Nephilim]</sup>: Your {{W40kKeyword|Infantry}} units (excluding {{W40kKeyword|Character}}) gain a new action each turn. If they move within 6" of the table center and end the turn with no units (excluding {{W40kKeyword|Aircraft}}) within 6" of them, you win 3 VP.
*''Repair Teleport Homer''<sup>[Removed in Nephilim]</sup>: Your {{W40kKeyword|Infantry}} units (sans {{W40kKeyword|Character}}) gain a new action each turn. If they move so they're totally within the enemy DZ and have them survive until your next command phase, you win 5 VP.

</tab>

<tab name="Warpcraft">
*''Mental Interrogation'': Your {{W40kKeyword|Psyker}} units gain a new power. During the psychic phase, they can cast this power on a 4+ on an enemy {{W40kKeyword|Character}} within 18" and gain 3 VP.
**In addition, if it exceeds the target's Leadership, you gain a CP. 
*''Psychic Ritual'': Your {{W40kKeyword|Psyker}} units can attempt a ritual if they're within 6" of the center of the map, keeping a tally for each successful cast. 3 VP for 1 Cast, 7 for 2 Casts, and a mere 12 for 3 and up.
**Not as garbage as when it first came out, but still a steaming pile of shit. The fact that it's affected by both Deny and Pseudo-Deny makes it risky to pop off as anyone with a brain will do their best to stop you. Also restricts your Psykers from doing better things unless you use faction-specific strats. 
*''Abhor the Witch'': You can't take any {{W40kKeyword|Psyker}} units for this. You gain 3 VP for any {{W40kKeyword|Psyker}} {{W40kKeyword|Character}} you kill and earn 2 VP for any other {{W40kKeyword|Psyker}} units you kill.
*'''[[Grey Knights|Suck it]], [[Thousand Sons|Nerds]]'''
</tab>
</tabs>

===Movement 101===
{{Main|Warhammer 40,000/Tactics/Movement 101}}

Topics covered so far:
*How movement works.
*Common rules mistakes.
*Basic advice regarding movement.
*Accurate and predictable measuring.
*Countering enemy movement.

===Psychic Phase (AKA: mind bullet time)===
Link to main article: [[Warhammer_40,000/Tactics/Psychic 101(8E)|Psychic Phase 101]]

===Terrain 101===
New as of 9th, pieces of terrain will all have certain traits.

*'''Cover:''' {{W40kKeyword|Infantry}}, {{W40kKeyword|Beasts}}, and {{W40kKeyword|Swarm}} models receive the benefits of cover from an Obstacle while within 3″ of an obstacle unless, when you resolve an attack that targets said model's unit, you can draw straight lines, 1mm in thickness, to every part of a model's base from a single point on the attacking model’s base (or hull) without any of those lines passing over or through any part of the obstacle.  {{W40kKeyword|Infantry}}, {{W40kKeyword|Beasts}}, and {{W40kKeyword|Swarm}} models receive the benefits of cover from Area Terrain while within it.  Nothing else gains the benefits of cover from the core rules with the possible exception of Dense Cover, which is discussed in that entry below.
**'''Dense Cover:''' If this terrain feature is at least 3" in height, then subtract 1 from the hit roll when resolving an attack with a ranged weapon unless you can draw straight lines, 1mm in thickness, to every part of at least one model’s base (or hull) in the target unit from a single point on the attacking model's base (or hull) without any of those lines passing over or through any part of any terrain feature with this trait. Models that are on or within an Area Terrain feature with this trait do not suffer this penalty if the only terrain feature these lines pass over or through is the terrain feature that the attacking model is on or within. Models within 3" of an Obstacle terrain feature with this trait do not suffer this penalty if the only terrain feature these lines pass over or through is the terrain feature that the attacking model is within 3" of.  This penalty is also ignored when the target is either W18+ or {{W40kKeyword|Aircraft}}.
***The Core Rules FAQ contains "Designer's Notes" which contradict the Core Rules on Dense Cover, but ''does not'' actually errata the definitions of Obstacle, Area Terrain, or Dense Cover:
****''Also, in the same way that Obscuring terrain ‘blocks’ visibility when it is in between the firing model and its intended target, Dense Cover terrain imposes a hit penalty whenever it is between the firing model and its intended target (with the noted exceptions). '''It is not required for a unit to be fulfilling the criteria of ‘gaining the benefits of cover’, as described for Obstacles and Area Terrain, for this penalty to hit rolls to apply''' (but also note that any rule that ignores the benefits of cover, or that ignores the benefits of cover that impose a penalty on hit rolls, would still ignore that penalty).''
***As a result, you need to discuss with your opponent how to interpret this.  Common options are listed below:
****The Designer's Note changes the conditions for Dense Cover to those of Obscuring Terrain: use the conditions for Obscuring (changing the height requirement to 3") and nothing else.  This means units on or within Dense Cover gain no benefit (just as they do not for Obscuring), but units "behind" Dense Cover benefit unless Aircraft or W18+, even if not Infantry, Beast, or Swarm.
****The Designer's Note adds to the conditions for Dense Cover such that both rules apply at once: under the conditions of Obscuring (changing the height requirement to 3"), all non-Aircraft non-W18+ benefit, and while on or within Dense Cover, Infantry, Beasts, and Swarms benefit (provided they are neither Aircraft nor W18+).
****The Designer's Note is ambiguous, so without explanation, has to be ignored.  Treat this text as not existing, and like Light or Heavy cover, only Infantry, Beasts, and Swarms benefit.
**'''Heavy Cover:''' +1 to armour saves against attacks made with melee weapons unless the attacked model made a charge this turn.
***As a practical matter, ''all'' heavy cover is also light (and hence none of it is dense).
*'''Light Cover:''' +1 to armour saves against attacks made with ranged weapons.
**As a practical matter, light and dense cover are treated by GW as mutually exclusive, and heavy is treated as light but moreso (some light cover is also heavy and all heavy cover is also light).
*'''Obstacle:''' Terrain you can be on but not within.  Has a series of traits that can be added on which in practice amount to "levels" of Obstacle:
*#Baseline: Doesn't have Exposed Position, Unstable Position, or Defence Line.  No additional rules.
*#'''Exposed Position''':  This will ''never'' have Unstable Position or Defence Line.  A model does not receive the benefits of cover if it is standing on this terrain feature. If you are behind it you may, though.  Can't be on Area Terrain because you can be within Area Terrain but not on it.  Note that this means the terrain will also deny cover to a unit on it that has a special rule granting cover - Exposed Position removes cover benefits even if the Obstacle doesn't grant them.
*#'''Unstable Position''' without Defence Line:  This will ''never'' have Unstable Position.  You can't stand units on top of this thing. No exceptions. You can walk them over it or through it, but not on top of it.  Can't be on Area Terrain because you can be within Area Terrain but not on it.
*#'''Defence Line''':  This will ''always'' imply Unstable Position (and hence can't be Exposed Position).  If an enemy unit is within 1" of this terrain feature, you can still make a charge move against it so long as the charging unit ends its charge move touching that terrain feature and within 2" of the target unit. Units are eligible to fight, and models can make attacks with melee weapons, if their target is on the opposite side of this terrain feature and within 2".  Doesn't actually require Unstable Position RAW, but because UP is the only kind of terrain where you can need this rule in order to engage, in practice is only found on some UP.
*Movement-modifying traits.
**'''Breachable:'''  All {{W40kKeyword|Infantry}}, {{W40kKeyword|Beasts}}, and {{W40kKeyword|Swarm}}s can move through any walls, girders, chains, or foliage of this feature without impediment - nothing else can.  As a practical matter, this usually means the listed units can easily move horizontally through Breachable terrain, while everything else has to pay additional movement to go over it.
***For unclear reasons, in practice 100% of Breachable terrain is also Defensible.
**'''Scaleable:''' Only {{W40kKeyword|Infantry}}, {{W40kKeyword|Beasts}}, {{W40kKeyword|Swarm}}s, and {{W40Kkeyword|Fly}} can be set up or end a move on top of an Obstacle with this (for anything else, it's functionally Unstable Position).  Likewise, only the same set of models can be set up or end a move on the non-ground floors of an Area Terrain feature with this trait (other models can only be set up or end a move on the ground floor). Finally, the terrain is Breachable with respect to a different set of features than actual Breachable (basically, features that would usually block ''vertical'' movement):  {{W40kKeyword|Infantry}}, {{W40kKeyword|Beasts}}, and {{W40kKeyword|Swarm}}s can move through the floors, ceilings, and gantries of this terrain feature without impediment.
***This means you'll never see terrain which is both Scaleable and Unstable Position (and hence you'll also never see Scaleable and Defence Line), as that would cause a rules paradox.
**'''Difficult Ground:''' Or rather, Difficult Terrain. Reworked to not be as crippling, this now only robs 2" of normal/advance/fall back movement and applies -2 to charge rolls for any that cross over it unless the entire unit has {{W40Kkeyword|Fly}} or it has {{W40Kkeyword|Titanic}} ''and'' the feature is less than 3" tall.
***For whatever reason, in practice all difficult ground is area terrain, even though in principle you could have difficult obstacles.
*Durability-enhancing traits.
**'''Defensible:''' Non-engaged {{W40kKeyword|Infantry}} units wholly within this (if Area Terrain) or wholly within 3" of it (if Obstacle) that are charged (if an Obstacle, draw a line 1mm thick between the closest parts of the bases or hulls of the two closest models in the two units; if the line passes over/through the Obstacle, then Defensible applies, otherwise it does not) can either hit with their overwatch shots on a 5+ (which doesn't enable overwatch, it just increases your accuracy if you are overwatching) or be barred from overwatch but gain a +1 bonus to hit in the next Fight phase.
**'''Inspiring:''' Units within 6" of this terrain piece gain +1 to Leadership. This can be locked to certain faction keywords so you don't have guardsmen being inspired by being near a chaos shrine or necrons inspired by statues of imperial saints.
**'''Obscuring:''' For your tall terrain pieces. Anything taller than 5" will block LOS for units on either side of it. However, it does nothing if either unit (the observer or the observed) is inside or on it, or if the observed unit's an {{W40kKeyword|aircraft}} or is W18+.


In the table below, under "Category", "Exposed Position" means an Obstacle with Exposed Position (and hence neither Unstable Position nor Defence Line), "Unstable Position" means an Obstacle with Unstable Position and neither Exposed Position nor Defence Line, and "Defence Line" means an Obstacle with Unstable Position and Defence Line.  "Area Terrain" is Area Terrain that isn't Difficult Ground and "Difficult Ground" is Area Terrain that is.

Cover is "Dense", which means Dense but not Light or Heavy, "Light", which means Light but not Dense or Heavy, or "Heavy", which means both Heavy ''and'' Light.  "No" simply means no cover.

"Breachable" is "Breachable" if both Breachable and Defensible, "Defensible" if Defensible but not Breachable, and "No" if neither.

{| class="wikitable sortable" style="margin-left:auto;margin-right:auto;"
|+ Terrain Features
! scope=col | Name
! scope=col | Category
! scope=col | Breachable
! scope=col | Cover
! scope=col | Obscuring
! scope=col | Scaleable
! scope=col | Inspiring
|- style="text-align:center;"
! scope=row | Armoured Containers
| Exposed Position || No || {{font color|Light|green}} ({{font color|Exposed&nbsp;Position|red}}) || No || {{font color|Yes|green}} || No
|- style="text-align:center;"
! scope=row | Barricades and Fuel Pipes
| Defence Line || {{font color|Defensible|green}} || {{font color|Heavy|green}} ||colspan=3| No
|- style="text-align:center;"
! scope=row | Battlefield Debris 
| Exposed Position || No || No ({{font color|Exposed Position|red}}) ||colspan=3| No
|- style="text-align:center;"
! scope=row | Craters
| Difficult Ground || No || {{font color|Light|green}} ||colspan=3| No
|- style="text-align:center;"
! scope=row | Imperial Statuary
| Unstable Position || No || {{font color|Light|green}} ||colspan=2| No || {{font color|{{W40Kkeyword|Imperium}}|green}}
|- style="text-align:center;"
! scope=row | Industrial Structure
| Area Terrain || {{font color|Breachable|green}} || {{font color|Dense|green}} || No || {{font color|Yes|green}} || No
|- style="text-align:center;"
! scope=row | Ruined Walls
| Defence Line || {{font color|Breachable|green}} || {{font color|Dense|green}} ||colspan=3| No
|- style="text-align:center;"
! scope=row | Ruins
| Area Terrain || {{font color|Breachable|green}} || {{font color|Light|green}} ||colspan=2| {{font color|Yes|green}} || No
|- style="text-align:center;"
! scope=row | Woods
| Difficult Ground || {{font color|Breachable|green}}  || {{font color|Dense|green}} ||colspan=3| No
|}

====Tactical Deployment====
Added in the Tactical Deployment Chapter Approved Mission Pack, this system adds points costs to terrain and enables them to be deployed by each side as if they were units; the point limit for deploying terrain is proportional to the size of the game (e.g. 50-100 points for Combat Patrol and 300-400 for Onslaught). Terrain deployed in this way will gain Terrain Abilities in addition to the normal traits, which grants them more complex effects than usual.

===Combat 101===
While Shooting and Fighting are separated below, they largely share rules, much like how Movement and Charging are in separate phases, but share many rules and concepts. By and large, ''any'' attack you make has 5 values: Attacks (which is rate of fire), Accuracy (typically WS or BS), Strength, AP, and Damage. These values are converted into other values in context (for example, attacks are left alone, but accuracy requires dividing by 6), then those values are multiplied together to determine how many wounds you actually expect to knock off your target. They resolve in this order, in general:

#Select a unit to make attacks.
#If these are melee attacks, determine number of attacks.
#For each model in the unit, select its target unit(s), which must be within range, and, if this is being done for shooting attacks, within line of sight.  Shooting attacks may target a different unit with each weapon and melee attacks may target a different unit with each attack, for determining how many targets to select - declare which weapons and how many attacks with each (if melee) are going against each target now. Proceed below for each model ''after'' all models have chosen targets.
#*Order of procession is pick one targeted unit at a time to be attacked, then cycle through each model that targeted that unit.
#*For each attacking model, proceed one profile at a time, grouping all attacks made with that profile together.
#If these are shooting attacks, determine number of attacks.
#Roll to hit, based on accuracy.
#Roll to wound, based on strength and toughness.
#Target rolls to save, based on its saving throws.
#*While all rolls are subject to re-rolls and modifiers, the most common modifiers in the game apply here, such as AP and Cover.
#Determine amount of damage by rolling and adding modifiers, if applicable.
#If the target has a "Feel No Pain" type rule, it rolls that against damage, much like a saving throw, on a per-damage-point basis. Feel No Pain rules cannot stack with each other - only the strongest one is applied. 

As will be discussed below, you ''always'' re-roll ''before'' applying modifiers.  Modifiers are applied in the following order: Replacement, Division & Multiplication, Subtraction & Addition, Ceiling (you always round fractions up to the next whole number).

====Attacks====
This can be random, such as 1d3, or 1d6, or 2d3, and can include an additive modifier, e.g. 1d3+3. There is a section below on dice averages, but for attacks, you can safely treat a random value as its average for the purposes of working out how much damage a given attack will do to a given target. More often, it will be a constant number- melee weapons generally use the Attacks stat of the user, while ranged weapons will specify the number of attacks they can perform in their profile.  Of special note are weapons with the Blast ability, as these weapons get a higher minimum amount of shots against larger units.

====Hitting====
By and large, this will be a WS or BS value. Regardless of the name of the stat, here called "AS" for "Accuracy Skill". 

The odds of hitting is: (7-AS-modifier)/6

*An ability to re-roll will multiply this value by (6+x)/6, where x is the number of facings on a hit roll you can re-roll, so if you re-roll 1s x is 1, re-roll 1s, 2s, 3s and 4s x is 4.
*Re-rolling all failed hits means x=7-AS, note that modifiers do not change the effect of re-rolling all failed hits, this is only affected by the AS. 
*Abaddon's ability to re-roll hit rolls even if they hit mean x=7-AS-modifier instead.

====Wounding====
Instead of requiring a fixed roll, like hit rolls, most wound rolls (WR) instead require that you compare the Strength of the weapon to the target's Toughness, although some weapons do require a fixed roll. 

Your wound roll (R) is 2+ if S ≥ 2T, 3+ if 2T > S > T, 4+ if S = T, 6+ if S ≤ T/2, and 5+ if T/2 < S < T.

The odds of wounding (oow) with a modifier to wound <math>m</math> are 
<math display=block>\begin{align}
oow &= \frac{\min\left(6,\max\left(1,7-R+m\right)\right)}{6}\\
    &= \frac{\min\left(5,\max\left(1,m + 3 + \left\lceil\log_{2}{S}-\log_{2}{T}\right\rceil + \left\lfloor\log_{2}{S}-\log_{2}{T}\right\rfloor\right)\right)}{6}
\end{align}</math>

This means S and T scale with twice the base 2 logarithm of their values, subject to the wounding caps on either end of always failing on 1 and always succeeding on 6 - for example, S8 results in a 3 in the formula twice (which will always be close to having added 6), while S4 results in a 2 twice (always close to +4).  If you were to pay for Strength on a linear scale - 1 point for S1, 2 for S2, and so on - the most cost-effective S would be 3, because it adds about 3.17 to your wound formula, and is the only S for which you add more than S to the formula.  This also means doubling your S (as many melee weapons do) is usually as good as adding +2 to the formula, but adding to your S directly (as most of them do) has very diminishing returns.

*An ability to re-roll will multiply this value by (6+x)/6, where x is the number of facings on a wound roll you can re-roll, so if you re-roll 1s x is 1, re-roll 1s, 2s, 3s and 4s x is 4.
**For re-rolling 1s, x is always 1, and so the multiplier is always 7/6.
**For re-rolling ''failures'', x is larger the more likely you are to fail; a WR of 6+ multiplies by 11/6, 5+ by 10/6, and so on down to 2+ multiplying by 7/6.  Remember, re-rolling occurs before modifiers, which is one reason why re-rolling wounds is better than re-rolling failed wounds - you can re-roll "successes" that will be failures after a modifier.
*In practice, T will usually vary between 3 and 8 - T2, T9, T1, and T10 are all very rare, and you can just assume absolutely no targets have T11+.  As S values increase, this results in diminishing returns, as the weapon becomes better at wounding T values it will never encounter.  This is generally most obvious when considering S6->S7, which is ''only'' useful against T6 and T7 in practice.

====Allocating Wounds====

After you have rolled to wound, the attack gets allocated to a model in the target unit.  Unlike in 8th edition, not only must this attack be allocated to any already wounded models, it must be allocated to whichever model in the unit has already had attacks allocated to it this phase, regardless if it actually lost any wounds or not.  Bear this in mind when it comes to weapons with different AP or damage stats.

====Penetrating Saves====
Basic saving throws work very intuitively, broadly identical to accuracy; a 6+ save works just like 6+ to hit - except that the target assigns which model takes the save in the unit and rolls the saving throw, which changes the looks of the math a little since we will be calculating how likely we are to penetrate our opponent's save rather than how likely we are to save. Many weapons have a negative AP value that increases the dice roll your opponent needs to beat to pass their saves, a cover save now adds a +1 modifier to the Sv of the unit rather than providing an alternate save like an invulnerable save like it did in the past. A saving throw roll of 1 is always a failure, but a roll of 6 is not necessarily a success. Invulnerable saves are unaffected by cover and AP but otherwise works exactly the same way as a normal save.

Your odds of penetrating (oop) are 
<math display=block>\begin{align}
oop &= \max\left(1,\frac{Sv - modifiers - AP - 1}{6}\right)\\
    &= \frac{\max\left(6,Sv - modifiers - AP - 1\right)}{6}.
\end{align}</math>
If your opponent can re-roll failed saves of x or less (so re-rolling 1s means x is 1, while re-rolling all failures on a final 5+ save means x is 4), your odds from above become:
<math display=block>\begin{align}
oop(x) &= oop + \frac{x\left(oop-1\right)}{6}\\
       &= oop\left(1+\frac{x}{6}\right)-\frac{x}{6},\\
     x &\le \max\left(6,Sv - modifiers - AP - 1\right).
\end{align}</math>

*Note that since AP is negative (-1/-2...) the outcome of AP is actually positive: -(-1)=+1. 
*AP increases damage linearly, which means having AP0 or AP-1 against a 2+ Sv and a 6+ Sv are very different things. Against a 2+ Sv AP0 will usually need 6 wounds to penetrate the save once, while AP-1 will need 3 wounds to penetrate the save once (causing 100%, i.e. 2x) more damage). Against a 6+ Sv AP0 will need 1.2 wounds to penetrate the save once, while AP-1 will need 1 wound to penetrate the save once (causing 20% more damage).
 
=====Cover=====
Light cover improves the armour save of the unit that is in cover by 1 against Shooting attacks regardless of which phase that Shooting attack is made in or whether the target or firing unit is in combat, and Heavy cover may give the same armour save bonus against close combat attacks. A model cannot claim multiple cover saves, it is either in cover and receives the bonus, or it is not, and it does not benefit. If you have a unit that is partially eligible for cover the whole unit will not benefit, but if you remove all the models from the unit that are not eligible the unit benefits immediately; therefore, it can be beneficial to roll your saves one at a time and pick off the ones outside cover first. 

*Certain units and terrain types (see terrain 101 above) have special rules which can affect chances to hit or visibility.

====Inflicting Damage====
When a model fails its saving throw it takes an amount of damage depending on the Damage characteristic of the weapon used. The model suffers that many wounds and any excess wounds are lost if not mortal; excess mortal wounds are allocated using the standard rules for allocating wounds, but since mortal wounds skip the saving throw step, you proceed immediately back to this step. If it is suffering both non-mortal and mortal wounds from the same attack, resolve non-mortal wounds first.

Feel No Pain "FNP" style abilities allow models to ignore some of the damage they take on by rolling a die and beating a number; these rules are exclusive, meaning you have to choose exactly one to use.  Some of these rules may specify that they work only on non-mortal wounds or only on mortal wounds, or in different phases, or what have you, but they generally all work the same.  This means that an FNP "save" is theoretically like an invulnerable save, but worse, as invulnerable saves are not negatively impacted by trying to resist greater damage values.  In practice, invulnerable saves are ''much'' easier to get.

Roll a die for each point of damage the model would suffer. On a roll of X or more (typically 6), ignore it.
*Sometimes, the roll is a 5+.
*A 6+++ FNP ''generally'' increases the average number of wounds you need to deal to a model to kill it by 6/5 or 20%. The chance that it will completely nullify an unsaved wound is 1/46656‬ for 6 damage, 1/7776 for 5 damage, 1/1296 for 4 damage, 1/216 for 3 damage, 1/36 for 2 damage, and 1/6 for 1 damage.
**This gets messy, quickly, because of how excess damage is wasted: while you will usually need 6 damage to kill a W5 model with a 6+++ FNP, it will actually suffer some damage between 0 and 5, as both 5 and 6 damage getting through kill it.  This means a W5 model suffering 6 damage actually takes about 4.67 on average (and has a 73.68% chance of dying outright), while a W1 model actually takes very nearly but not quite 1 damage, with the same chance (nearly 1, which is nearly 100%) of dying outright.  Meanwhile, a W6 model without an FNP takes 6 damage, with a 100% chance of dying outright (in this case, making it 'less'' durable than the W1/6+++ model).  Generally speaking, W is better for resisting lower damage (W6 can't die to D5, while W5 can, regardless of FNP), while FNP is better for resisting greater damage, relative to some starting W.  
*A 5+++ FNP increases the average number of wounds you need to deal to a model to kill it by 6/4 or 50%. The chance that it will completely nullify an unsaved wound is 1/729 for 6 damage, 1/243 for 5 damage, 1/81 for 4 damage, 1/27 for 3 damage, 1/9 for 2 damage, and 1/3 for 1 damage.

This means you can ''usually'' roll the dice for all of the non-mortal wounds a model is suffering at once, as order does not matter - enough failures to remove the model's remaining wounds kill the model, and the excess is wasted - but remember that special rules can apply (such as a model that only gains an FNP after it suffers some damage, or a weapon that lets non-mortal wounds spill over to other unit members).  You can't do this for mortal wounds in a unit with mixed FnPs, as each time a model dies, the unit's controller can choose a new model to start suffering remaining mortal wounds.

===Shooting 101===
====The basics====
#Shoot at something until it is DEAD/destroyed/exploded/gone/**cked/smeared-across-the-floor. Seriously. Anything that is not dead can still hurt you. As the old Tactica Imperialis says: "Concentrate your fire on one target to the exclusion of all else. Once it is gone, choose your next target." Consider heavily before you commit several turns worth of shooting into a big target like a Knight with your lascannons, you might be better off ignoring the Knight and targeting a Leman Russ instead if you cannot kill the Knight in one turn.
#Shoot for the mission. At the end of the game each game is won based on Victory Points (VP), don't fall for the distraction carnifex. 
#Shoot your weapons with the highest Damage characteristic first, if you deal a wound to a unit of Terminators with your Tactical Squad's bolters leaving one Terminator at one wound and then fire your Overcharged plasma into that squad with Damage two you are wasting 1 damage. If you had shot your plasma first you would get an extra damage for free. The opposite situation exists, if your opponent has a wounded model in a unit it can make sense to try and remove that model with your lower damage weapons in order to get maximum value of your bigger weapons into the next model in the unit. 
#Shoot with the unit with the fewest targets available first. At the start of your shooting phase, assess what target options each one of your shooty units has, and always have your units who only have a single option fire first. The reason for this is if you've got unit A in a position to shoot anything he likes and unit B which only has one thing to shoot at, you want B to take the shot first. If you shoot B's target with A first instead, you run the risk of destroying it or breaking their morale, and you'll feel like a complete moron for depriving B of anything to shoot at.
====Blast Math====
Every faction has access to weapons with the Blast special rule, which sets the minimum number of shots a ranged weapon can fire to 3 when targeting a unit of 6 or more members, and to the maximum value of its shots when targeting a unit of 11 or more.  Here is the math on the size of the benefit for a variety of numbers of shots; note that a single weapon that shoots 2d6 times will get less benefit than two weapons shooting 1d6 each, and that if your first weapon reduces the target below a size threshold, the second weapon will lose out. Generally speaking, any other mechanics that improve rate of fire, such as re-rolling the dice, stack with Blast but have diminishing returns. 

{| class = "wikitable"
|+ Blast Benefits
! Number of Dice (X) !! Sides !! Average Result !! Result vs 6-10 !! Benefit vs 6-10 !! Result vs 11+ !! Benefit vs 11+
|-
| 1 || 3 || 2 || 3 || 50% || 3 || 50%
|-
| 2 || 3 || 4 || 4.11.. || 2.78% || 6 || 50%
|-
| 3+ || 3 || 2X || 2X || 0% || 3X || 50%
|-
| 1 || 6 || 3.5 || 4 || 14.29% || 6 || 71.43%
|-
| 2 || 6 || 7 || 7.0277.. || 0.40% || 12 || 71.43%
|-
| 3+ || 6 || 3.5X || 3.5X || 0% || 6X || 71.43%
|}

What this means defensively is that if you are worried about being hit by blast weapons, you should not typically field units of size 6-7 (as they will die ''faster'' than units of size 5) or 11-17 (same deal, but compared to 10).

===Assault (Charging and Fighting 101)===
*Note that you can charge any number of units, but unless your charge roll allows you to end up in engagement range of <b>every</b> unit you chose, your charge will fail. 
*A charge roll is usually 2d6, which gives you an average roll of 7, a 1/36 chance of rolling 12+, 3/36 chance of rolling 11+, 6/36 chance of rolling 10+, 10/36 chance of rolling 9+, 15/36 chance of rolling 8+, 21/36 chance of rolling 7+, 26/36 chance of rolling 6+, 30/36 chance of rolling 5+, 33/36 chance of rolling 4+, 35/36 chance of rolling 3+ and 36/36 chance of rolling 2+. 
*When you charge, all models can be moved in any direction, including backwards, towards an objective, on top of a building or towards an enemy unit you did not charge; the only rule is that the unit has to end the charge move in coherency, in engagement range of every unit you declared a charge against, and outside of engagement range of any other enemy units. This is effectively free movement you can use for anything; even if you are a shooting unit, this can let you get to where you need to be. Just charge a unit with little threat in terms of overwatch/melee and you get 2d6" of free movement. You get an additional 3" of free movement before and after a unit fights; the key different here is that you can end these moves within 1" of a unit you did not charge. Use this to your advantage, but those units will fight back, so take care to stay 1" away from melee units. 
*Take care to stay more than 3" away from enemy characters if you don't want to engage them; otherwise they will be able to heroically intervene and move up to 3" and engage you in combat, even if you did not charge them. Many Imperial Knights are characters, meaning they can heroically intervene as well. Some units can heroically intervene 6" - Space Wolves and certain Imperial Knights, for example. Adeptus Custodes can charge you in your charge phase as well with their jetbikes, so watch out for these things!
*Players go back and forth each picking one unit at a time to fight with, starting with the player whose turn it '''isn't''', although chargers strike first and generally abilities that allow you to fight at the same time as chargers are resolved starting with the player whose turn it '''is''', so pick your first unit to fight carefully; after this your opponent can use a stratagem to immediately fight with one of their units.  If a unit is within 1" of an enemy unit at the end of the fight phase, it can fight if it has not already done so, so if your opponent uses a stratagem to fight again and engage your units that have not yet fought, they now get to fight. If a unit is more than 1" away from enemy units and it did not charge, it will not be able to attack; take care not to allow your opponent to remove the models from one unit which another one of your units would have liked to fight against. Generally, pick the unit with the fewest models within 1" and fight with that first; your opponent will have a harder time removing the models that are within 1" of your 20 Genestealers than your Hive Tyrant. 
*Charging units may only attack enemy units that they charged, or that performed a Heroic Intervention that turn.  So your consolidation move will not allow you to strike at other units, even if you use an ability or stratagem to allow them to fight again.

====Advanced Notes====
*Sometimes a shooting unit can be as valuable in melee as a dedicated melee unit; most units cannot fall back and shoot. Simply engaging an enemy shooting unit with your transport or shooting unit can hold it up for a turn.
*As a general rule of thumb, you want to break or destroy your enemy in your opponent's assault phase. That way, your opponent does not have a shooting phase before your assault teams move towards their next target.
*Generally speaking, Overwatch is more of an annoyance than a true threat, especially now it is a stratagem, though certain rules, bonuses, etc. (Defensible terrain, Tau Supporting Fire/Counterfire Defensive Systems, flamers, etc) can take their toll, especially if you're relying on glass cannon units (Harlequins, notably). Some special "Negate Overwatch" powers exist, but there are other ways to mitigate the effects of Overwatch. Unlike 7th, there is no limit to what can fire overwatch or how many shots. Wyverns, for example, fire their regular 4D6 shots. Granted, they hit on 6s, but this can still hurt. During Overwatch, any ability that lets you re-roll all misses is ''much'' more effective.
**Overwatch takes place before you move your charging unit, and is still subject to normal rules for Line of Sight, cover, range etc. Moving a Rhino or other vehicle flat-out to block off models from shooting your chargers is always a valid trick.
**If blocking Line of Sight is not an option, then aim to eat the overwatch. One way to do this is to have a "tanky" unit lead the vanguard. For example, when charging a unit armed with multiple flamers, have a fast monster/walker lead the charge. Heck, throw a Rhino at your enemies before charging with those Assault Terminators.
** An easy way to ignore Overwatch is to charge a model with '''FLY''' from behind LOS-blocking terrain (aka the 1st floor of a ruin if you're using ITC rules) because the model ignores moving through terrain. You do not need LOS to declare a charge, but your opponent always needs LOS to use Overwatch.
*Remember that generally pile-ins use the same overall rules for charging, and thus any unit must ultimately maintain coherency. When attacking a large spread-out unit, you can negate a lot of its strength by attacking on opposing flanks.  The thing to bear in mind is:  You can only finish a pile in or consolidate move closer to the nearest enemy model (which means if you are already in base to base contact you cannot move).
*The ability to quit close combats is a very powerful ability, especially if you are {{W40kKeyword|TITANIC}}. 
*In multiple or extended combats, casualty removals via pile-in are very tactical. By careful removal of casualties you can force enemies to pile-in in the direction YOU want them to.

===Vehicle Tactics===
Ever since 8e made vehicles nothing more than a keyword which changes how some rules apply to them, vehicles require no special tactics other than what you would apply to other models except that they will be able to shoot your assault unit in the face i their next turn.  Also, watch out for {{W40kKeyword|TITANIC}} units that can fall back and still shoot.

===Morale 101===
A unit can lose additional models in the morale phase; failing a morale test by rolling over your Leadership with 1d6 + the number of casualties the unit has taken this turn means one of your models flees.  A morale test of 1 always passes. If you fail the test (i.e. a model fled), you take combat attrition tests: roll for every remaining model in the unit, applying -1 to the result if the unit is below half strength after that model was removed.  For each 1, another model will flee the unit.  These rolls are "Combat Attrition Tests".  After that, if your unit is not in coherency, you must choose models to flee until the unit is in coherency.

Fleeing means that a model counts as destroyed, but does not trigger any rules that would respond to its destruction when it flees - instead, it will trigger rules that respond to fleeing. 

*The morale phase happens after the psychic, shooting, and assault phases and any casualties from those phases are added together when testing morale.

====Morale Mathhammer====

In general, a unit with Leadership "Ld" that has taken "C" casualties this turn will pass a morale test with the following odds:
*Ld >= 6+C:  6/6 (automatically passes)
*6+C > Ld >= C+2: (Ld-C)/6
*C+2 > Ld:  1/6

For example, Ld 10 means a unit with 5 or fewer models will always pass a morale test unless some other rule intervenes, because it can't take more than 4 casualties and still take a morale test, and after 4 casualties, the final member will not have to roll.  On the flip side, for a very large unit, say, 30 members, any practical Ld value will quickly become meaningless as casualties rack up, and you'll end up relying on the baseline 1/6 odds of passing.

If a unit fails, it will lose 1/6 of its remaining members if it is still at or above half strength, or 1/3 otherwise.  Due to this, even starting unit sizes are ''generally'' more efficient than odd ones: here is how many casualties several unit starting sizes have to take to take combat attrition tests with a penalty (i.e. before the morale test that must be failed in order to proceed).  Remember, a unit at 1 more member than below half strength will take combat attrition tests with the penalty, because that 1 model will flee before the tests are taken.  A 0 means the unit cannot take combat attrition tests.

#0
#0
#1
#2
#2
#3
#3
#4
#4
#5

And so on; in general, going from an odd number to an even number of models increases the number of casualties you have to take to be below half strength, while going from an even number to an odd number does not.  The only exceptions to this are going from 1 to 2 (neither unit will ever take a combat attrition test) and going from 2 to 3 (a 3 model unit can lose its third member to a combat attrition test).

===Dice Roll Math===
*It is almost always better to re-roll dice than to get +1. For instance, re-rollable 4+ has almost a 10% edge over 3+.
**The exception is re-rolling 6s, which is 1/36 worse than 5+.
**Because of how people throw dice, a re-rollable 2+ has a lower chance than math suggests. People tend to use the same rolling motions, which means those dice often end up in the same position ("1" both times). So use a dice tower or roll your dice more thoroughly for a longer period of time in order to increase randomness and adherence to estimates made via mathhammer. (this bullet should be deleted - this is only true in highly refined laboratory experiments as it requires that starting conditions be the same across consecutive dice rolls - initial die facing, height, surface, etc etc)
*The average roll on 1d6 is 3.5, and the average roll on 1d3 is 2.
**The average of XdY is X*1dY, so 2d6 is 7, 3d6 is 10.5, etc. 
*Picking the highest of 2d6 adds about 1 (actually 35/36) to the average roll.
*4+ re-roll 5+ is the same as 3+.
*Re-rolling 1s is always equivalent to multiplying your odds of succeeding by 7/6, which means, additively speaking, it's better the higher your original odds are: you'll get an extra success in every 12 dice for a 4+, 9 dice for a 3+, and slightly more than 7 dice for 2+ (actually 7.2).
**Re-rolling all failures has a larger benefit the lower your original odds; you'll get an extra success every 4 dice for a 4+ base, every 4.5 (i.e. 2 successes every 9) for a 3+, and every 7.2 for a 2+.
*The odds of getting a 9 or more on 2d6 is 10/36, a little less than a third (27.78%). Re-rollable, it's a bit less than half (47.84%)
*And, if you're into it, there's [[MathHammer]].
*GW dice are not mathematically fair! This set of mathematical data presumes you are using perfectly balanced casino dice which are. See following for details. http://www.dakkadakka.com/wiki/en/That%27s_How_I_Roll_-_A_Scientific_Analysis_of_Dice