I'm Mome Borogove. In addition to playing 40K:Inquisitor, I also sometimes dabble in building helpful tools or collecting useful information for the community.
As people are reaching the seasonal end-game, a few have mentioned struggling to deal enough damage to keep up with -90% or -99% reduced damage missions. Usually, they already know to push their crit stats up and leverage battle-state or debuff-dependent bonuses, but one thing they may not know about is the power of vulnerability and vulnerability effectiveness.
I figured I'd try to lay out what these two stats do and why they're so effective at pushing out more damage: