Well I've tried what you guys said and for normal missions it seems to be working but for events like cathedral and (ranked, which shouldn't be used) and boss fights, the damage output still ends up being pretty low.
So like with the underworld boss fights when I set the multiplier to x1, x2, x3, x4, and x5; they still just gave me the same numbers as the multiplier, same as if I changed it to 60, 70, or 80. So maybe theres limits?