First we start with the basics of status effects – EnP wiki has already an extensive list of all the existing buffs currently in the game, as well as which heroes are capable of these effects.
List of all buffs
But what we want to talk about is this:
Which buffs can stack, how they stack, and which buffs you want to stack.
As a rule of thumb, buffs that share the same icon cannot stack.
Everything is written here in the first two posts by Dave Cozy