Psyker
This weapon Blocks both Melee and Ranged attacks. Additionally, Block Cost is reduced by 22.5-30%.
Up to 14-20% Strength, scaling with Peril.
1-4 Burn Stack(s) on Critical Hit to a maximum of 3-12 Stack(s).
4.5-6% Close Range damage on Repeated Hit. Stacks 5 times.
Illisi/Accatran/Assail/Bubble/Disrupt Destiny. Ranged build with emphasis on support and good ranged uptime.
Bubble uptime and spending your Assails are the bread and butter of this build, so long as you don't rip through your ammo too fast you should be able to spend most of the mission firing darts and las shots from inside a shield, supporting allies with toughness regen and a barrage of ranged attacks.
I would recommend casting bubble often to get a hang for it as the cooldown is low, and remember you can hold your ability button to show where you are aiming the bubble. Important things to consider with the build:
1. Use Assail a lot! It's free and building Perils for Warp Splitting and Warp Rider talents makes literally all of your damage sources more effective. Assail also saves ammo and is great for clearing groups of unarmored and flak targets, just spam the primary fire as the alt fire is pretty meh all things considered (costs more Perils and is slower to shoot for negligible amount of extra damage and ability to aim it)
2. Keep pace with the party frontliner! You should most certainly not be the guy fighting from the front but keeping up with whoever is leading means you can support them and have the best opportunities for good bubbles. Placing the bubble slightly ahead of the party as a fight starts so you can advance into it is great, as well as hunkering on high ground where you can leisurely snipe out shooters, elites, and specials.
3. Accatran is a great weapon but can chew through ammo if you aren't careful. You do not want to be taking too much ammo from the vets or gunlugger ogryn in the group, so stick to Assail unless you are A. out of darts or too high Perils to continue, B. need to snipe an enemy quick that Assail couldn't properly target, or C. are fighting carapace where Assails will just bounce off and your best option is building burn stacks from Infernus perk on your rifle.
4. While I chose Illisi for the build you can definitely swap to Deimos if you prefer it. Illisi isn't really for horde clear cause Assail and Accatran already smoke groups, it's for another anti-carapace option and faster special attack animation that isn't as committal as Deimos.