2.5-4% Bonus Critical Chance on Chained Hit. Stacks 5 times.
Hitting at least 3 enemies with an attack, increases your damage by 24-36% for 3 seconds.
Target receives 1-4 Stacks of 2.5% Brittleness on direct projectile hit. Debuff lasts for 5 seconds and can have a maximum of 16 stacks.
3.5-5% Critical Chance for every 10% of magazine spent during continuous fire. Stacks 5 times.
On boss: Invis>Take position>Krak>Unload into weakspot.
Pick any melee weapon, that you are comfortable dealing with mixed hordes and surviving (Shovel, Devil sword, Heavy sword).
If you are struggling with sniping specials, drop Close Quarters Killzone(bottom right) and get Suppression immunity from left bottom tree.
P.s. for the love of god, dont shoot bolter into hordes >.<