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

===Angels of Death===
*'''And They Shall Know No Fear:''' Re-roll failed morale tests. Not going to come into play that much with your generally good Ld scores, but given how punishing Morale can be it's still a good way to ensure your units don't run off, especially for your already small-ish unit sizes & 2W Primaris. And Apothecaries cannot revive models who fled instead of being slain.
*'''Bolter Discipline:'''  Models using a Rapid Fire bolt weapon can double their number of shots (i.e. ''rapid-fire'') if at least one of the following conditions is met. They don't stack (no triple or quadruple shots if you meet more than one condition). The conditions are:
**The target is within the weapon's half range (normal Rapid Fire).
**The model is {{W40kKeyword|infantry}} and every model of its unit remained stationary during the previous Movement Phase. ''If a Devastator's Heavy Weapon marine moves, the Sergeant cannot use Bolter Discipline on his boltgun''.
***It gives your marines the option to commit to those objectives instead of having to get close to the enemy. Factions like T'au may have long ranged small arms, but Space Marines are the only army that can rapid fire from full 24"-''30"'' away.
**The firing model is a {{WH40Kkeyword|Terminator}}, {{WH40Kkeyword|Biker}}, {{WH40Kkeyword|Centurion}}, {{WH40Kkeyword|Dreadnought}}.
***This right here is the good shit. Footslogging terminators now have a significantly improved threat capacity, bikers are somehow even more deadly fast than they already were, and both Centurions and certain types of dreadnoughts have access to hurricane bolters, AKA 12 shots apiece.
*'''Shock Assault''': A brand new buff for Space Marines, if a unit with this rule charges, gets charged, or performs a Heroic Intervention, models in the unit add 1 to their Attack characteristic until the end of the turn (meaning +2A if they can fight twice like with a stratagem). Like Bolter Discipline before it, this will be available to all flavors of Space Marines (including all three of the Chaos varieties), and gives the generally lackluster melee of most Primaris infantry and chainsword assault marines a little bit of a boost. Killer on units with power weapons like Terminators. Also means foes have to be a bit more careful about charging at Tacticals and such to tie them up, more so if you use larger units, and that they can assist in a melee in a pinch. 
*'''Combat Doctrine''': Feel like it's 7th edition all over again. Each of the three Combat Doctrines gives an AP-1 buff to different weapon types in your armies (non-cumulative with buffs from other sources). You have to use each Doctrine in order, starting with the '''Devastator Doctrine''', and once you switch there's no going back, so pay attention to the rhythm of the game. Your ''army'' gains this if ''all units in it'' have this rule, meaning taking a Guardsman Battalion or even a single Assassin CP'd in right before the battle would prevent the SM detachment from getting this rule, but allied SM detachments are ok even from a different chapter.
**On top of that, Chapter supplements give First Founding Chapters (and their descendants) a Specialist doctrine that is a bonus active on top of the regular doctrine. Bringing chapters with different specialist doctrines prevents either from getting theirs.
**These nifty rules will make your marines more efficient killers, but their rotation makes them predictable - devastate -> advance -> assault. Savvy opponents may try to break LoS to force movement penalties on your heavy weapons, rush for melee while you're still under the ranged doctrines, then fall back when you're finally under the assault one, scale buildings, etc. As such, don't be predictable yourself. Remember, you don't need to switch doctrines on the same turn they become available: surprise drop pod a target turn one or advance your infantry under cover of Devastation while your enemy remains confined to their hiding spots turn 3, what have you. The doctrines are as follows:
*#On Turn 1, your army will always start with the '''Devastator Doctrine''' turned on, giving all your Heavy and Grenade weapons the extra -1 AP so that you can soften entrenched infantry and cripple enemy vehicles from afar in preparation for your advance. Remember the first points of AP are the most important ones: AP-2 Heavy Bolters and Assault Cannons are more noticeable than AP-4 Lascannons. Do keep in mind the plethora of sniper rifles and Heavy Flamers (Incendium/Inferno/Flamestorm cannons) are Heavy Weapons too. The boost to Grenades matters only to Intercessors for the most part.
*#On the 2nd turn you switch to '''Tactical Doctrine''', shifting the boost to your Rapid Fire and Assault weapons. Be it to close the distance to the enemy or because your vehicles are about to give their last, this mostly passes the ranged baton to your infantry. And a bolt rifle going from AP-1 to AP-2 is more noticeable than a lascannon going from AP-3 to AP-4. Storm bolters and auto bolt rifles work wonders here. 
*#On the 3rd or 4th turn you shift to '''Assault Doctrine''' (you MUST change to assault on the 4th turn) giving the extra AP to your Pistol and Melee attacks. Don't. Forget. Your. Pistol. The first point of AP is the most important one - chainsword/CCWs benefit the most, while AP-4 on a sword can become excessive.
**As of the 02/27/20 FAQ, you MUST change from Devastator to Tactical on turn 2, and then change to Assault on turn 3 or 4. This will force you to keep at least a few units that are capable of fighting in CQC, as you can no longer just bum around in Devastator or Tactical doctrine and persist on blasting things from across the map.