Time to delve into the true power of the Primaris. No not those ones… the one in the Astra Militarum Codex.
That’s right, let’s look at the full might of the Primaris Psyker. Who has the power to not only bestow much needed command points for your list, but also comes with two psychic powers from the Psykana discipline. And since they’re dirt cheap, you can include as many as you like and get some psychic might with which to smite the enemies of the Imperium. You can also pick up the Wyrdvane Psykers or Astropaths if you want–though not as powerful as Primaris Psykers, they too have the power of the Immaterium at their beck and call. They can unleash powers like:
Terrifying visions is pretty decent if you know you’re able to capitalize on leadership tests. But leadership is one of the easiest things in the game to negate–the Guard can pull in Commissars and have a psychic power that lets them ignore morale for a unit, the Tyranids have synapse creatures, Marines’ they shall know no fear lets you reroll failed morale checks, even the Tau have an ability that lets them auto-pass leadership checks if they need to. And in a pinch, they can spend 2 command points to pass that crucial check if they need to anyway. Still, being able to reduce the leadership of an enemy that can’t cheat their way around it can make even a light volley of fire incredibly deadly, which means that you can dedicate the full might of your army elsewhere if you can leverage this right.
Gaze of the Emperor is your standard Line of Doom. Reach out and touch those characters, give them a mortal wound, probably. Not bad if you can get your Psykers in close where they need to be–though by the time you’re within 2d6″ it gets real risky for the oft-fragile psykers.
The last of the Index-based psychic powers. This one is a pretty solid mainstay because you can give it to units that can benefit from Take Cover, giving them an additional +2 to their saving throws–or even up to a +3 if you’re able to get them to Take Cover in cover. The Militarum have some incredibly nasty ways of increasing their defense without even really having to try. Especially since you’ve got another psychic power that can further buff your defense.
Not only will you be able to give your units +1-3 to their saves fairly regularly, you can also make it nigh impossible for your enemies to hit. Drop a -1 to shooting rolls on top of units that have their saves buffed to keep them in the fight much longer and at full capacity while you attrit your enemy into despair. For more fun, drop it on a Leman Russ that’s Striking and Shooting from a critical position and watch as the enemy fails to hit it.
The other reason that powers like the Terrifying Visions aren’t super great. If you’re running low on Commissars for some reason, your Primaris Psyker can help keep your models in the game. Finally we’ve got:
This one is kind of cool–it has some subtle benefits. It’s not restricted to the closest unit, so it can be good for putting Mortal Wounds onto a character. You don’t even have to have line of sight to the target–they just have to be within 18″ of the Psyker. Now it does need a 7+ to go off, and you have to roll decently to put out more than a mortal wound or two, but if you’re getting in there with your Pyskers you can suddenly snipe characters that should otherwise be protected by virtue of their plot armor. Which can be a nasty surprise if the enemy is unprepared.
All that said, you’re still probably better dedicating yourself to defense first. The Militarum’s strength is their numbers, they’ve got a lot of flexibility and firepower, and if you’re able to shore up their already decent durability, you can make them practically unkillable for the turn or two it’ll take you to wipe your opponent off the map. All in all, those defensive powers seem fairly strong, and, with the ranges on them and careful planning, you can try and keep your enemy from denying you outright.
Well that’s a brief rundown on Psychic Powers. These are the ones the Guard have access to, though you can always take another detachment with some psykers from the Space Marines if you want to toss some Librarius powers around. Get the most out of that Imperial Keyword.
And remember, the difference between the Emperor’s Mercy and the Emperor’s Justice depends on which side of the psyker you’re on when it all goes awry.