Far as I am aware dots are not affected by glancing blows and critical avoidance. Meaning that monster dot attacks will be many times more powerful than everything else.
Fortunately, there are only 2 monster types that seem to be a problem - bitterwings and soul cages. They seem to have a sort of a dot channeled attack that does significantly more damage than everything else, including bosses (apart from the monolith bosses themselves which are supposed to be strong).
Thing is, there can be multiples of them. Taking the damage of 3 soul cages at the same time, something fairly common, is an almost certain death unless you kill them instantly. The bats might be more bearable but considering they can spawn with blue mods their damage potential can be even higher.