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

==Psychic Powers==
Like all 8E factions, in addition to Smite, you have access to a faction-specific table of powers. The Librarius Discipline has power for pretty much every situation, but they're mostly niche enough that it's difficult deciding upfront which powers to take - two of them are mortal wound causers which are worse than Smite, three are friendly buffs you can use to help dictate the flow of combat, and one is a really powerful debuff that usually won't go off but can be a gamechanger when it does activate.

With the advent of the new Codex-plus-chapter-supplements model, each chapter will also have access to a second, Chapter-specific psychic discipline for extra flavor, made available as each supplement rolls out. Combined with the Obscuration discipline for Phobos Librarians, that will be a choice of 3 different potential sets of psychic powers that you'll have access to. Bring a different Librarian for each and pretend that you're playing Thousand Sons.

Unfortunately, as of the new Codex, your buffing powers now specify {{W40Kkeyword|CHAPTER}} instead of {{W40Kkeyword|ADEPTUS ASTARTES}}, so you can no longer spread buffs across to other Chapters.

===Librarius===

#'''Veil of Time (WC6):''' Select a whole {{W40Kkeyword|<CHAPTER>}} ''unit'' of any kind 18" away from the user; until the start of the next Psychic Phase that unit re-rolls charge and advance rolls, and also gets Always Strikes First. So it's not only offensive by letting you reach your opponent faster, but it's also defensive, in case you get charged by a swarm and want to stay in melee. 9" charges are still below a 50% chance at 47.84%, so if you sorely want it to charge right after deepstriking go play {{W40Kkeyword|Black Templars}} instead, although you can combine it with a CP re-roll. If you combine it with the successor tactic for +1 to charge rolls, it instead brings your odds of charging from 41.67% to 65.97%, although after accounting for the odds of failing the power, your overall odds of making the charge drop to 59.22%.
#'''Might Of Heroes (WC6):''' Until the next Psychic Phase, a single {{W40Kkeyword|CHAPTER}} ''model'' of any kind within 12" gains +1S, +1T, and +1A. An awesome power if you have a special snowflake that is already insane in combat (like a dreadnought), makes a powerful character turn into the hulk. Jokes aside, this power is better for challenges than for murdering rank and file, as the strength and attacks will ensure hits and wounds get to your opponent, and the toughness will blunt the attack of your opponent should they survive. Can also be used to help ''manipulate your opponent into picking a different target'' to bring down - if you have two heavy targets, like Land Raiders or Dreadnoughts, up front to be shot, and you put this on one of them, your opponent will usually kill the other one, and dictating the flow of battle is always useful. Furthermore, boosted Leviathans and Super heavies are just nasty.
#*''DON'T FORGET'' to use this power to save vehicles that need saving. Perhaps none of your characters or dreads are in positions to beat things up in melee, but you have a predator next to your librarian that could REALLY benefit from being T8 for a round of your enemy's shooting. Even if the S and A go to waste, the extra T can help keep your big stuff alive.
#*Can transform OK sergeants with heavy melee weapons into a force to be reckoned with: an Assault Squad sergeant with an eviscerator can better wreck a tank than a Primaris Lieutenant's power sword with the same boost.
#'''Psychic Scourge (WC6):''' Make a Leadership + 1D6 contested against the Leadership + 1D6 of an enemy unit within 18" of the psyker. If you beat the enemy, they take D3 mortal wounds; equal them and they take 1 Mortal Wound, and nothing happens if your total is lower. A tad less powerful than Smite, but it's better for sniping characters since it isn't restricted to the closest enemy unit. Plus, it can be used in addition to Smite to spam mortal wounds.  Best used in combination with something that inflicts a Leadership penalty to the target or a Leadership bonus to the psyker, if you brought any.
#'''Fury of the Ancients (WC7):''' Range 3D6" (average 10.5, but don't trust it), so less than 18" Smite. Target any visible enemy ''model'' within that range and draw a line from the caster to that model; each enemy ''unit'' under the line, in addition to the target model's unit, takes a mortal wound. Needs good positioning, but it's not restricted to the nearest unit like Smite is, and can affect multiple units with at least 1 MW.  The biggest problem is the random range: while you can usually count on it to be at least 10", lower values can happen - you need to be within 3" of your primary target if you want to guarantee they'll be in range.
#* Suffers drastically from attacking units with larger base sizes, as they will eat up more of the power's random range.  You should avoid this power if at all possible; the positioning necessary to make it work is easily on par with Smite's, and its output is substantially worse.
#'''Psychic Fortress (WC5):''' Select a {{W40Kkeyword|<CHAPTER>}} ''unit'' 18" away from the user; until the start of your next Psychic Phase, that unit automatically passes morale tests and gains a 4+++ FnP against Mortal Wounds caused by psychic powers. Mostly protection ''against'' Smite, as marines already have high re-rollable morale. Like with Might of Heroes, if your opponent brought psykers, this can be used to manipulate them into attacking the target of your choosing.
#'''Null Zone (WC7):''' Until the start of your next Psychic Phase, enemy units within 6" can't take invulnerable saves, and cut the results of their Psychic tests in half. Powerful against enemies that ''depend'' on their invulns or psychic powers, like Harlequins, Hive Tyrants, Daemons, and Storm Shield MEQs; not so much against heavily armoured units like Terminators.  Remember, you need to get the librarian to within 6", not 1" - don't be afraid to Advance into position and let other things do the murder work for you. Combos insanely well with the Burning Blade relic.

===Obscuration===

These powers can only be used by Vanguard Librarians. They don't do much damage, but god damn can they fuck with your enemy. Tenebrous Curse and Mind Raid are easy to cast and excellent for damaging and trapping or even finishing off enemy characters - free choice of targets (unlike Smite), 1MW each, and either halve all movement or generate CP in the process. Considering most regular HQs clock in at 5W, a successful psychic phase with only one Phobos Libby means they're down to 3W and too slow to pull away. And no one tries to rush down the center with a beatstick that's half dead and moving at a snail's pace, making this a good deterrent.

#'''Temporal Corridor (WC6)''': Pick a friendly {{W40kKeyword|CHAPTER}} {{W40kKeyword|Phobos}} unit within 3". It can move as if it was the movement phase; it must advance and cannot fall back, but when advancing it rolls 3d6 and picks the highest for the distance it advances. Cannot be used on a given unit more than once per psychic phase. HELLO Reivers!
#*Slightly more situational than Warptime, but no less amazing for it. 
#*Consider using it on a newly deep-struck (using the strat) librarian with Null Zone to put his target within the 6” range.
#'''Soul Sight (WC6)''': Pick a friendly {{W40kKeyword|CHAPTER}} {{W40kKeyword|Phobos}} unit within 18". Until the start of your next psychic phase, that unit re-rolls all failed hits when using their ranged weapons. Also allows attacks from ranged weapons to ignore cover. 
#'''Shrouding (WC6)''': Pick a friendly {{W40kKeyword|CHAPTER}} {{W40kKeyword|Phobos}} unit within 18". Until the start of the next psychic phase, enemies can only shoot that unit if they're the closest target as if the unit was a Character, but since they don't gain the character keyword your opponent can't just get around it with snipers; psychic powers can still target them, though. 
#'''Hallucination (WC6)''': Select a visible enemy unit within 18". Its Ld is reduced by 1. The opponent must also roll 2d6, and if the result is higher than the unit's highest Ld, all its hit rolls take a -1 penalty. 
#'''Tenebrous Curse (WC6)''': Select a visible enemy unit within 18" that does not have the {{W40kKeyword|Fly}} keyword. It takes a mortal wound. Additionally, its Movement stat is halved, as are all of its advance and charge rolls. Scarily effective on Death Guard.
#'''Mind Raid (WC6)''': Select a visible enemy unit within 18". It takes a Mortal Wound. If your army is Battle-Forged and the power targeted a {{WH40Kkeyword|character}}, roll 3d6. If the result is greater than or equal to the target's Ld, you get a free Command Point! Will make Conscript spammers and Renegades and Heretics players scream in fury as the re-rolling dread destroys their mind-raped infantry horde.