Psyker
25-40% Cleave on Hit. Stacks 5 times.
45-60% Finesse Damage for 2s on successful Dodge.
3.5-5% Critical Chance on Weak Spot Hit until your next Critical Hit. Stacks 5 times.
1-4 Burn Stack(s) on Critical Hit to a maximum of 3-12 Stack(s).
Force greatsword for horde clear and elite focus. Brain burst to peek corners. Recon lasgun to fill in and for ammo efficiency. Use Scrier's Gaze immediately off cooldown. Crazy crit chance means crazy toughness and move speed from Mettle. A little ammo intensive even with the recon lasgun. Most melee weapons and guns should thrive with this build, and it only needs a little touch-up for use with a staff.
If you're wanting to use a staff I, personally, would swap out "Tranquility through Slaughter" and "Surety of Arms" for "Soulstealer" and "Perfect Timing". In the case of Infernus staff though, I would take "Perilous Combustion" in place of "Perfect Timing" to ensure that soulblaze stacks are melting absolutely everything they can be and that you're getting toughness for it.