Quote Originally Posted by Garnatian View Post
I am sure I checked this before and DoTs were retroactive with buffs, but I shall go check again.
The potency applies to what your stats are at the initial time it's cast, never during. I tested it mostly with Regen. If I cast Regen, then use Cleric Stance, it still ticks for the same general number. But heavily decreases if I cast it with Cleric Stance already on.

Same goes with defensive buffs. If you receive a DoT, THEN use a defense buff, there's absolutely no damage mitigation versus the DoT.