It really is though. It's the same argument as thorn, in that it prevents regen, and it's very unavoidable, unlike the Lightning grenade. If you compare it to its arc counter part, the damn thing does like 60 damage and no lingering damage, but they are essentially the same mechanic. Stop relying on your favorite grenade and own up to the fact that it's stupid good. Shouldn't matter anyway because bungo loves warlocks too much to nerf them