Ok, I'm about to give up, I can't figure out how it works.
As far as I understood it, it triggers x magic damage, where x is the stacks of burned applied, whenever damage is dealt to any monster(basically time stands still until then) but it has a weird working with PISORF, if I PISORF the burned guy and it gets damage, the Burned damage is applied (and the stacks stay), if I use it on the burned guy and he gets no damage, no burn damage is applied, if I use PISORF on any other monster, the burn damage is applied (even if PISORF caused no damage) and the burn stacks are removed.
Is this working as intended?