Zealot
70-100% Rending on Backstab Hit.
45-60% Finesse Damage for 2s on successful Dodge.
5-8% Strength for every 10% of magazine spent during continuous fire. Stacks 5 times.
Direct hits apply 1-4 Stacks of 1% Brittleness for 5s. Stacks 20 times
If your team already has a purgatus staff and enough horde clear, you can run the updated combat shotgun agrapinaa (Flak/Maniac) (Full Bore/No Respite) and use it for sniping specials and what not. Most important part of build, ABUSE THE BACKSTAB MECHANIC, especially if you have a taunt ogryn. If you get good enough with it you can get a book back in 5 seconds on a good setup.