Editing Warhammer 40,000/8th Edition Tactics/Tau (section)

==Wargear==
===Melee Weapons===
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HAHAHAHA NOPE! Generic melee weapons are for other armies.
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HAHAHAHAHHAHA
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===Ranged Weapons===
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Expect a lot of S5 AP0 weapons, with a couple of High damage low output weapons on the bigger units, all of which come with above-average range.  
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'''Infantry / Drone'''
* '''Pulse Weapons:''' your S5 D1 guns at various ranges.
** '''Pulse Pistol:''' 12" range and a pistol, in other words it grants you 1 shot at S5 per model in your shooting phase while in combat. Granted, you should not be getting into close combat but if you somehow survived an assault, your opponent can get hit by this in your next shooting phase from your Fire Warriors (if you paid the 1pt per model to bring them). Usually it's better to just fall back and let your other units punish whatever came at you, but if you can't disengage then consider having pulse pistols on half of your guys to give that melee unit an emergency punch.
*** As of Faith and Fury the above is more relevant than it’s ever been. Night Lords have a compliment of stratagems and relics that used in tandem will: Deny Overwatch, make charges out of deep strike easier, and prevent falling back. In other words, the Three Golden Uh-Oh’s of playing T’au. Still a very weak solution to a niche problem compared to how many loyalist marines you should expect to face, but know that you at least have something you can do instead of just give them light pats. (Assuming they all didn’t run away last turn because, y’know, Night Lords.)
** '''Pulse Rifle:''' The original, the best. 30" rapid fire smackdown, stacks ''wonderfully'' with sept traits, wargear and warlord traits granting extra range and shots.
** '''Pulse Carbine:''' Doesn't pin targets anymore, but is assault 2 at 18". Changes to assault weapons in 8th make them kinda dicey shooting on the run at BS5+ on your pathfinders. Gun drones get two of these.
** '''Pulse Blaster:''' the pulse shotgun found on your breachers, start at a assault 2 bolter at 15" end at S6 ap-2 under 5" Very risky, but that's life on a breacher team.
** '''Longshot Pulse Rifle:''' Found on sniper drones, big range and can target characters, dealing mortal wounds on 6+ to wound. Still sucks due to only being S5 and AP0, which pretty much all characters can take without blinking. Stacks with the abilities from a spotter. Note that despite having 'pulse' in the name, these do not benefit from Volley Fire.

Another viewpoint: It really depends on the army you are facing. Strength 5 shots will wound most characters on a 3+, and AP requirements vary between armies.

* '''Markerlight:''' There's a whole section above for the effects these have, but they're almost a rather literal heavy 1 <s>flashlight</s> laser pointer.

* '''Rail Rifle''': Pathfinders only. The smallest source of Mortal Wounds currently available to Tau, each squad may take up to three of these weapons if they don't take an Ion Rifle. They're generally a better call for hunting MEQs, TEQs, and Monstrous creatures thanks to their AP and ability to deal mortal wounds on a 6+ to wound.

* '''Ion Rifle''': Pathfinders and interceptor drones only. The second type of special weapon available to Pathfinders, this weapon acts like every other Ion weapon, in that it can be overcharged to deal potentially more hits and damage. Not bad at 4 points for a S8 shot.

* '''Photon Grenade:''' It's a D6 grenade, but it doesn't do any damage. Instead it gives the attacker -1 to hit in the proceeding fight phase. Absolutely amazing with the T'au sept, as the spam means you're bound to get that juicy -1 to hit in overwatch.

* '''Kroot Weapons:'''
** '''Kroot Rifle:''' It's basically a boltgun that has a close combat bonus.
** '''Kroot Gun:''' It's a rapid fire autocannon, but does D3 damage instead of a flat 2. Found on the Krootox.

* '''Neutron Blaster:''' the vespid gun, used for burninating armour at S5, AP-2.

'''Battlesuit'''
* '''Airbursting Fragmentation Projector''': A Weapon that ignores line of sight. Okay, but unless you need to ignore the line of sight, such as on very terrain laden maps, the ''Burst Cannon'' outperforms this weapon.

* '''Burst Cannon''': The cheap Dakka that it always has been. 4 Shots at Str 5 and 18". You might want to give your suits some other (and more expensive) options as all your drones and Fire Warriors will provide Str 5 shooting en masse. Actually, with an advanced targeting system, you can make these work very effectively. Note that commander with 3 bursts+ATS is good, but crisis suit loses too much dakka, and unless you're shooting terminators, giving up a burst cannon for ATS is a downgrade in raw power.
** If you want the -1 AP from Advanced Targeting Systems to actually match a Heavy Bolter's profile, the best you're going to get are 12 shots. Still, that's more than enough to scare most troop choices shitless.

* '''Cyclic Ion Blaster''': 3 (almost) Autocannon shots at 18", this gun's default mode outperforms the Plasma Rifle per point outside of its Rapid Fire range against [[MEQ|HEQ, GEQ, MEQ, and TEQ]]. Using the Overcharge profile gives you extra Strength and Damage making it second only to the Fusion Blaster against multi-wound models and vehicles, the downside being that Overcharge deals a mortal wound to the bearer upon rolling any number of modified 1's to hit. Markerlights let you re-roll natural 1's to hit which mitigates a bit of the threat, and if you manage to get 5 Markerlights on the same target you can't suffer this downside.
** Note that the CIB is only superior to the Burst Cannon when you are overcharging it. If you do not expect to overcharge, consider 3 BC+ATS instead.

* '''Flamer''': Standard flamer in every respect. Deadly when combined with advanced targeting system (though just taking another flamer is better statistically if you are going for an all-flamer loadout (statistically 2 flamers +ATS does about the same vs MEQ and GEQ, but once you get up to TEQs, the ATS starts to show it's worth). Just don't waste it on commanders unless you crave the OMAE WA MOU Coldstar shenanigans.

* '''Fusion Blaster''': It's a Meltagun, which means it deals 1D6 damage (best of 2 under half range) and being Tau Empire gives you a lofty 6" more range than those silly primitive Imperial ones for 25% more points. Second most expensive option, but the clear winner against anything with more than a couple wounds. Your primary source of antitank and monsterhunting, due to ridiculously low damage-per-point ratio of broadsides and hammerheads.

* '''Missile Pod''': It went up in price considerably and being able to deal D3 wounds doesn't quite make up for it. Still a decent choice, but is outperformed by a Cyclic Ion Blaster unless you're not willing to risk the overcharge on anything T6 or above. Or if you actually want a weapon with range, as it has twice that of the CIB (and the longest range option of the Commander and Crisis Suits).

* '''Plasma Rifle''': Your go-to cheap option against heavy infantry, melting away 3 points of the enemy's Save. At 1 extra point over a Burst Cannon it's cheap, but will struggle against multi-wound models as it only does 1 damage a shot.
** Received a subtle nerf with the reintroduction of Overcharge mechanics. The selling point of Tau plasma was that, while it was weaker, it wouldn't suffer '''Gets Hot!''', now that nobody suffers that particular penalty without overcharging their weapons, there is no reason for Tau plasma to be S6 if everyone else can put their plasma out at S:7 without blowing themselves up, so yes, GW actually made Tau plasma the ''worst'' plasma.
** A little bit better with the Bork'an sept tenet, which can keep it out of charge range whilst being able to fire twice. Also, the only gun for crisis suits that actually does work with this sept.

* '''High-Intensity Plasma Rifle''': Farsight got a weapon upgrade. More AP, double the damage and 6" more range.

* '''Broadside Weapons:'''
** '''Heavy Rail Rifle:''' You get two S8 AP-4 D6 wound shots at 60" and deals mortal wounds on top of the other damage if you roll a 6+ to wound. 8th edition favours quantity over quality when it comes to shooting, and most targets you'd want to shoot this at have invulnerable saves anyway. It's hard to justify taking this instead of the HYMP, unless you need the extra range.
*** '''UPDATE''' Thanks to the new Magna Rail Rifle prototype weapon systems, this thing just got a new lease on life. 3 Broadsides armed with Rail weapons, Smart Missile Systems and Seeker Missiles will net you around 300 points for a serious heavy armor killer. 
** '''High Yield Missile Pod:''' Heavy 4, S7, AP-1, D3 missile pod. Broadsides take two of these instead of a single HRR. Does D3 damage compared to the HRR's D6(+1MW on a 6+ to wounds), meaning that if all shots hit, a pair of these can do up to 24 Damage, across 8 targets, compared to the HRR's 12 damage (+2 MW) across 2. Almost always the better of the two weapons, with the exception of targeting something like a Tank Commander which lacks an invulnerable save.

* '''XV9 Weapons''':
** '''Double-barrelled Burst Cannon (Forge World)''': Twice the shots for a 60% price increase. Bit of a bargain right there.
** '''Phased Ion Gun (Forge World)''': An Assault plasma rifle with worse AP (unless it rolls a 6+ to hit), Strength, and Range, but has the potential for more shots. Since it is a bit more expensive than a Plasma Rifle, and less reliable, you probably want to skip this.
** '''Fusion Cascade (Forge World)''': A Fusion Blaster with 66% less range, but the potential to fire 3 shots. Also 60% more expensive. Cheaper than the equivalent amount of FB Crisis suits, but slightly less effective as the number of models increases.
** '''Pulse Submunitions Rifle (Forge World)''': 30" range, 2d3 shots at S6, for 20% more than a burst cannon. If you don't need the range, take the DBBC instead.

* '''Monstrous Suit Weapons'''
** '''Ion Accelerator:''' Two different shooting modes. Both are a wonderful 72" range but are Heavy D6. Standard is S8 with D3 dmg, while Overcharge gives you S9 and 3 damage. Nova Charge changes the type to Heavy 6 (for both Standard and Overcharge modes).
** '''Heavy Burst Cannon:''' 36" Heavy 12 S6 AP -1 D2. Becomes Heavy 18 on Nova Charge. Coupled with ATS this is a very powerful weapon, and easily worth taking on your Riptides.
** '''Cyclic Ion Raker:''' Heavy 6 shots at 24" range at S7. Disappointing AP-1 and D1 damage, though; overcharge buffs to S8 and Dd3 Damage. Not as bad as it appears on first glance, the pure volume of Dd3 shots provides flexibility and performs similarly to a fusion collider outside of melta range. Increases noticably with ATS.
** '''Fusion Collider:''' S8 AP-4 Heavy D3 shots at 18" doing the standard melta thingy with its D6 damage.
** '''Pulse Submunitions Cannon (Forge World):''' 60" Heavy 3D3 shots, dropping S6 AP-2 D3 hits. Nasty!
** '''Ion Discharge Cannon (Forge World):''' Curiously, this Ion weapon doesn't have a basic overcharge profile outside of Nova Charging. Regardless, short 12" range dishing out mortal wounds to vehicles if you roll a 6 to-wound; normal profile is Heavy 3 S8 AP-3 D1, and Nova Charge is Heavy 3D3 S10 and flat 3 damage.
** '''Phased Plasma-Flamer (Forge World):''' the scary gun found on the Y'vahra, 8" Heavy 2D6 autohits at S6 AP-2 and 3 damage on the standard profile holy shit! Nova Charge gives you another D6 shots; not much but still insane!
** '''Flechette Pod (Forge World):''' how is this not standard battlesuit equipment WTF Tau?! Pistol D6 S4 shots at 6"; for the time being only found on the Y'vahra until the Earth and Fire Castes figure out how goddamn useful this is is.

'''Vehicle Weapons'''
* '''Smart Missile System:''' Heavy 4 pulse rifle that can hit targets out of LoS from the shooter. Most things that can take them get two, which is great.

* '''Seeker Missiles:''' 72" Heavy 1 S8 AP-2 DD6 with one use per missile. At only five points it doesn't seem like a bad investment; could mean the difference between bringing that scary unit really low or killing it. They work wonderfully on Hammerheads, who can hit on a 2+ with Longstrike's buff. They need the target to have at least two markerlight shots on them to use the firers BS though, otherwise they ONLY hit on 6s and it doesn't take a genius to know that that's not worth doing unless you're in a desperate situation.

'''Hammerhead Weapons'''
* '''Rail Gun:''' A single-shot weapon on an expensive chassis, with two 72" profiles. Solid shot does an S10 AP-4 D6 damage shot that throws down with a mortal wound on a to-wound of 6 on top of normal damage. The dreaded submunition puts out D6 S6 AP-1 D1 hits. If you take Longstrike, his +1 to wound makes an overcharged Ion cannon a better choice overall... unless you consider that his +1 to wound will trigger mortal wounds on 5+ and he has a straight up 82% chance of wounding TEQs (assuming you have 1 markerlight on the target)- good for triggering focused fire.

* '''Ion Cannon:''' Standard and overcharge modes at 60". Standard puts out 3 S7 AP-2 D2 shots while overcharge does D6 shots at S8 and 3 damage with the standard overcharge risk. If you want to use Hammerheads (aside from Longstrike or FW options) then this is THE gun. Against T7 Sv 3+ vehicles, it does almost 50% more damage than the railgun when supported by markerlights and Longstrike (synergy is the name of the game for Tau).
* '''Twin Heavy Burst Cannon (Forge World):''' an absurd amount of shots (16 to be exact) at S6 AP-1 D1 and 36". You will chew through most infantry with ease with this gun.
* '''Twin Fusion Cannon (Forge World):''' 24" Heavy 2 S8 AP-4 and D6 damage with melta.
* '''Twin Tau Plasma Cannon (Forge World):''' Got the "Tau" stamp in order to differentiate itself from other plasma cannons, Heavy 4 S7 AP-3 D2 at 48". A strong competitor to the Fusion and Ion Cannons.

'''Flyer Weapons'''

* '''Quad Ion Cannon:''' very disappointing, the gun has basically been reduced to a reaper autocannon, which aren't even any good in the CSM army. Overcharge helps out a bit, granting +1 S D3 damage and D6 shots.

'''Tidewall Fortification Weapons'''

* '''Supremacy Railgun:''' As Soild Shot Railgun profile, but with 2 shots. 

'''Titanic Weapons'''
* '''Pulse Driver Cannon:''' Better with the codex, now doing Heavy D6 shots instead of the measly Heavy D3 from the Index. Still sporting a powerful 72" S10 AP-3 D6 damage. 

* '''Pulse <s>Blastcannon</s> ARC Cannon:''' 3 range modes to choose from, with number of shots and stopping power increasing and decreasing with range respectively. Short range hits with a tremendous S14 AP-4 and a savage 6 damage, but only at Heavy 2 at 10"; Medium range is still pretty hardcore at S12 AP-2 D4 but double the shots and range over close range; lastly, long range triples the range and shots, but decreases the power down to S10 AP0 and D2. Try to ignore the range bands and focus instead on what sort of targets you should be hitting with this gun.
** '''Heavy''' 2, this gun qualifies for the Bork'an Sept Tenet. It's not a lot at 30-36", but at 10" - 16" this pretty much means you don't have to be in charging range of anything that could tie you up in melee while you try to bring the thunder down.

* '''Cluster Rocket System:''' 4D6 shots at 48" and S5, but no bonus damage or AP to speak of. Still, that's a shitload of shots for smacking the shit out of tarpits within range.

* '''Destroyer Missiles:''' Seeker missiles with a foot of range lopped off, shooting a single shot and on a hit they do D3 mortal wounds. Practically mandatory to be used alongside Markerlights as without two they will only hit on unmodified 6's.

* '''Heavy Rail Cannon(Forge World)''': Macro weapon. Single shot at S18(!) with 2D6 damage. Inflicts an additional D3 Mortal Wounds on a Wound Roll of 6+. Also comes with the Cluster Shells ability, that has a 4+ chance to deal a Mortal Wound to any <b>Model</b> that ends a charge within 3" of the carrying unit.

* '''Tri-Axis Ion Cannon (Forge World)''': 9 shots of TEQ killing goodness, that can be overcharged into busting vehicles.

* '''Fusion Eradicator (Forge World)''': 5 shot Fusion Blaster, with an extra 6" range.

* '''Pulse Ordnance Multi-Driver (Forge World)''': Macro weapon. Choice of profiles between 6 shots at S12 + 4dmg, or 2D6 shots at S8 + 3dmg. Given the law of averages, You should not ever use the secondary profile.

* '''Nexus Meteor Missile System (Forge World)''': Macro weapon. 2D6 shots at S10 and 4dmg, with a minimum range of 24" and maximum range of 120".
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===Support Systems===
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Secondary wargear for battlesuit type units, not usually worth replacing a weapon for, but can be when taken in addition to them. 
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* '''Advanced Targeting System''': Improves the AP of all weapons on the suit by 1, turning those Burst Cannons into sawn-off Heavy Bolters. For Commanders it is generally more effective to do so, albeit more expensive. You don't want to replace a weapon for ATS on a normal Crisis suit, it is a damage loss.
** The FAQ changed the AP of the default close combat weapon to "0", so this now affects the melee on the suits. Take it on your Stealth Suits to give them a AP-1 melee attack along with their Burst Cannons. Also makes Commanders even more dangerous in melee.
**3x more expensive on the Ghostkeel, Riptide and Stormsurge, though they don't replace any systems for it and all have a ''lot'' of guns, so possibly still worth looking at.
* '''Counterfire Defence System''': Allows re-rolls to hit when firing Overwatch. Give it to your Tau Sept suits and you'll be re-rolling Overwatch on 5+ which makes a HUGE difference for charging units. Normal units have a 16% to hit on overwatch. Tau Sept units with this have 55% - better than BS 4+, which is the standard for our army. 
** '''Note:''' Since the Stormsurge is a {{W40kKeyword|VEHICLE}} this can be combined with the Point Defence Target Relay Stratagem (makes overwatch hit on 5s and 6s). Tau Sept Stormsurges have this already, but useful for the other Septs.
* '''Drone Controller''': All {{W40kKeyword|<SEPT>}} {{W40kKeyword|DRONE}} models near (6" bubble) any bearer get +1 to hit rolls. You can put this on a Commander or Crisis suit and buff Sniper, Markerlight, or Gun drones. Usually requires a critical mass of drones to be effective. A critical mass of gun drones is all you need to mow down infantry, swarms, and screens. Stick this on your Shas'Vre crisis suit dude!
** '''Note:''' Drone Controller's area of effect is based on the size of the Battlesuit's base. So a drone controller on a stealth suit (32mm round) can affect less drones than a drone controller on a Stormsurge (170mm oval). 
* '''Early Warning Override''': Get a free shooting attack on one unit that is deployed (deep striking) within 12" but at -1 to-hit, so only at 5+ with any suit apart from the Commander and don't even think about overcharging those CIBs. Very seriously worth taking on a team of Crisis suits, giving them Missile Pods, or Burst cannons/Plasma Rifles if you want to go cheaper. Keep them on Riptides for extra denial. Works with Velocity Tracker and, as with the Drone Controller, base size of model equipped will increase area of effect.
** Twice as expensive on the Ghostkeel, Riptide and Stormsurge, but these are very shooty models with large bases, and so will create a very impressive bubble of Fuck You Dakka if your opponent is still insistent on throwing his Terminators away.
* '''Multi-tracker''': If a model shoots all its weapons at the same target, it may re-roll 1's to hit. One Markerlight can give this to your whole army. The target unit now also has to include at least 5 models for this system to work. Also only works in your shooting phase. Oh and it got more expensive in the Codex. So it went from bad to absolutely terrible. 
* '''Shield Generator''': The classic 4+ invulnerable save. Riptides still can't take this, but it's cheaper than before for all other suits. Shower thought: Crisis suits can get Iridum armor and this for a 2+/4++ to mock those pesky Custodes.
** Costs 30 points on the Stormsurge and a whopping ''40'' on the Y'vahra. Obviously not worth it on the later, since it already has a 5+ Invuln that jumps up to 4+ against Melee and close ranged attacks in addition to its Drones, but the Stormsurge is painfully lacking a Invulnerable save, so unless you're planning on burying it behind every single Shield Drone you can take, you'll likely be shelling out for it anyways.
* '''Target Lock''': Enables the suit to ignore the to-hit penalties for Advancing and firing Assault weapons, and moving and firing Heavy weapons. Also allows firing Rapid Fire weapons after Advancing at -1 to hit. A cheap way to potentially increase your suits' mobility by a good amount, and reduce reliance on Markerlights. However, you will likely never want to take this on a Commander or Crisis suit, as removing the -1 to hit gives you the same number of hits you would have from another gun. While lowering your damage if you don't advance. Can be useful for Coldstars, to take advantage of the 20" move, and Broadsides so they can move and shoot without penalty. Stealth suits will mostly see better returns from the ATS. Almost an auto-take on Ghostkeels/Riptides as both their big weapons are heavy, meaning you can ignore the penalty while you jump around the board.
** This has the same effect as shooting at a target with 4 markerlight counters on it, but getting 4 markerlights takes an average of 8 pathfinders. That's 64 points total, a Target Lock is ''much'' cheaper. Plus Pathfinders are usually the first thing to go in our list.
** Remember this costs double on the Ghostkeel, Riptide, Stormsurge and Y'vahra, but given how many guns those suits carry, that's honestly not surprising.
* '''Velocity Tracker''': +1 to hit when targeting units with the {{W40kKeyword|FLY}} keyword. Against dedicated flyers, this just counters their -1 to hit '''Hard To Hit''' ability; however skimmers and jump infantry now also possess the {{W40kKeyword|FLY}} keyword, so you can also use the bonus against Jetbikes, skimmers, Assault Marines and anything else that jumps or hovers. A good investment in those cases as you get it basically for free at two points, particularly on units where you can take support systems on grunts without losing a weapon system slot (such as Stealth Suits or Broadsides).
** It is less cost efficient on the usual suspects (Ghostkeel, Riptide, Stormsurge and Y'vahra) at 10 points, but, again, those models carry lots of guns and give up nothing to take this. 
** Pay particular attention to this one for units with effects that trigger on 1s or 6s to hit. A +1 to hit completely eliminates the chance of blowing yourself up with your Ion gun. Sadly, this does not help your wound rolls, so you still need that 6 to get the bonus wound.
** Worth a serious consideration on both Broadsides and Stormsurges, or even a unit of Crisis/Stealth Suits
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===Signature Systems===
Also known as your relics. Please note that you cannot give any of these to Kroot units. Although why you would ''want'' to give a relic to a Kroot Shaper is beyond me. 

* '''Puretide Engram Neurochip''': Once per battle, you can re-roll a single hit roll, wound, or damage roll made for the bearer or a friendly {{W40kKeyword|<SEPT>}} unit within 6" of the bearer. In addition, if your army is battle-forged and the bearer is on the battlefield, roll a d6 each time you or your opponent use a stratagem, on a 6 you gain a bonus command point. The first ability isn't amazing, per-se, but it's not bad and it might help you out of a jam. The second ability is far more worthwhile if you expect your opponent to spam low-cost stratagems, giving you plenty of chances at bonus command points.
** RAW this ability triggers during deployment or other pre-game phases as long as the bearer is already on the field, so deploying the bearer first against armies dependent on deployment/infiltration strategems can pay off in a big way.
** This relic is all but guaranteed to pay for itself, assuming you spent 1 CP to take it and reasonably expect to spend at least 1 CP on a reroll during the game. And that's not even accounting for the CP you generate from it.
* '''Onager Gauntlet''': {{W40kKeyword|Battlesuit Commanders}} only. The old donkey punch is a single S10 AP-4 d6 D attack in melee ideal for cracking open tanks, but you only get one attack and a WS of 3+ really hurts your chances of actually killing anything with it.
* '''Multi-sensory Discouragement Array ''': Enemy units within 6″ subtract 1 from Leadership. Skip.
* '''Solid-Image Projection Unit''': {{W40kKeyword|Ethereal with hover drone}} only. Once per phase, if declared as the target of a charge, the Ethereal can move up to 3″ before the charge is made. Amusing, but if something is trying to charge your Ethereal, he's dead meat anyway. Save your slot for something useful. *Insert Dr Zoidberg sound*
* '''Seismic Destabiliser''': At the start of each shooting phase, you may either pick an enemy Infantry unit claiming cover or a Building within 12″ of the bearer; the Building suffers D3 mortal wounds. If targeting the infantry squad, roll a die per squad member. On a 6, they suffer a mortal wound. Might be decent for weakening blobs, but you've got better choices. Against a 30 model Boyz Mob, its about 5 dead Orks--however, most large units are barreling forward and not in cover. 
* '''Supernova Launcher''': Replaces an Airbursting Fragmentation Projector. 18″ Assault D6, S6, AP-2 2D. can shoot targets that are out of line of sight. Good for pot shots on hidden primaris and the like.

===Prototype Weapon System===
Like the Tyranids, instead of picking one Signature Systems, you can give any '''unit''' one of these, which will replace all of its equivalent weapons when available. Note that they aren't relics but you can use the multi-relic strat to generate up to 3 of these.  Likewise, none of them displace ''actual'' relics, so you can put a relic plus one of them on the same unit. Some of these affect all models in the unit, so all 10 of your Crisis Suits can gain bonuses. Consider this when sticking something on a single commander (They are making less appealing options very appealing: Crisis Suits in all configurations, Railguns of all forms, and Ion Accelerators).

* '''Accelerated-photon Grenades:''' Unit with Photon Grenades. In addition to a melee penalty, the Photon Grenades also prevent them from advancing and halves their charge rolls. Lasts until your next turn, so you can throw one in the shooting phase instead of waiting for overwatch.
** The duration our regular photons cry out in dismay for.
* '''Advanced EM Scrambler''': {{W40kKeyword|Ghostkeel Battlesuits}} only. Enemies that deep strike cannot set up within 12" of the user. For if you don't need more firepower but want to shut down deepstrike with the Ghostkeel's big base. Proper positioning and use of cover with this baby using Infiltrator can give your army a beautiful 28” (including base size) deep strike denial bubble, much to the chagrin of any DS heavy army.
* '''Amplified Ion Accelerator:'''  {{W40kKeyword|XV104 Riptide Battlesuit}} only. Replaces the Ion accelerator. Each setting deals 6 attacks, Standard deals D3 and Overcharge deals D3+1d3, along with AP-4. Notably, This allows you to use your Nova Charge on other abilities while firing with increased output.
* '''Annihilation Warheads:''' {{W40kKeyword|KV128 Stormsurge}} model only.  The units Destroyer Missiles auto-deal 3 MW when they hit. Consider each Stormsurge has 4 D missiles, this means 12 potential mortal wounds.. Not bad.  
* '''Cross-linked Stabiliser Jets:''' {{W40kKeyword|Commander}}, {{W40kKeyword|XV8 Crisis Battlesuit}}, or {{W40kKeyword|XV8 Crisis bodyguard}} unit only. You may re-roll hit and wound rolls of 1 for this unit. Really useful on flamers, burst cannons, and CIBs especially. Gets better in larger units.
* '''Fusion Obliterator:''' {{W40kKeyword|Ghostkeel Battlesuits}} only. Replaces the Fusion Collider. 24" Heavy 3 S9 AP-4 D1d6 (melta). Almost doubles your output against high-wound targets, but probably not worth a relic slot.
* '''Gatling Burst Cannon:''' {{W40kKeyword|Commander}}, {{W40kKeyword|XV8 Crisis Battlesuit}}, {{W40kKeyword|XV8 Crisis bodyguard}}, or {{W40kKeyword|Ghostkeel Battlesuit}} unit only. Each Burst Cannon in the unit gets replaced with a version that scores another hit for each unmodified 6. This is better than +1 to hit in that it works on BS2+ models (commanders or anything BS3+ shooting at a 5 markerlight target) just fine, as well as applying to Overwatch. Gets better in larger units.
* '''High-Capacitance Railgun:''' {{W40kKeyword|TX7 Hammerhead Gunship}} unit only. Replaces the Railgun. Reduce the range to 60" but increase the number of shots for Solid shot to 2, and Submunition to 4D3 shots.
** Not worth it at all. With no invulnerable save to speak of and the inability to benefit from savior protocols it '''will''' get destroyed quickly. If Hammerhead squads were a thing, then it'd be pretty good. But as of now they don't exist.  
* '''High-Powered Incinerators:'''  {{W40kKeyword|Battlesuit}} unit only. Replaces all Flamers. They become S5 when at half range (usually 4"). Being as flamers are cheaper than Burst Cannons and can still benefit from ATS, this makes them very comparable, just note that playing in close like this pretty much assumes the unit will get shot up badly. Distraction Carnifex? 
* '''Magna Rail Rifle:'''  {{W40kKeyword|XV88 Broadside Battlesuit}} unit only. Replaces the Heavy Rail Rifle. +1S (so S9), and 1s and 2s for damage count as 3s. Now you can generally threaten Tanks and T8, while also taking on multi-wound targets with ease. When compared to the HYMP, these are all the more appealing given that they are half the price. 
** Stack Kauyon and Command and Control node to wipe your opponent's vehicles off the map turn one. 
* '''Networked Markerlights:''' {{W40kKeyword|Pathfinder Team}} unit only. Turn Markerlights into Assault weapons. Makes your Markerlights mobile and synergises with Assault weapon buffs, but you need a big Pathfinder team to justify this over other Systems.
** Don’t let that Assault profile fool you, if you’re taking you’re only doing so to get out of the penalty for moving and firing Heavy weapons, that extra 1”-6” isn’t worth the shooting penalty (Vior’la being the exception). 
* '''Reactive Countermeasures:''' {{W40kKeyword|Battlesuit}} '''''model''''' with Airbursting Fragmentation Projector only. Ignore AP of -1 or -2 against this model. Something to consider solely for the massive amounts of AP -1 a marine army can spit out nowadays thanks to doctrines. Anything AP -3 or higher should be handled by your drones or shield generators. Use this, a Shield Generator, and Iridium Armor for a frustratingly hard to remove target that is unfortunately carrying a piece of shit gun.
** Because of order of operations, you can give a model a projector, then this, then the relic projector Supernova Launcher just fine. And CIBs!
*** Note that this only affects shooting attacks and not melee.