It happens to land enemies too, rarely, but every second creep under the water gets out of combat, randomly, and regenerates to full. It’s the most frustrating thing ever to battle 2 kraits with the thief, get low, and see your enemies regenerate to full while you do not. I’ve been trying to get in Mellagan’s Grotto for a while now, but every krait there regenerates constantly. It doesn’t happen when I stealth, they do that right in the middle of combat.