Does the 20% extra power on healing effects granted by Demon Armor/Skin boost the amount of health you gain from Drain Life, or is it only a flat 2% total health rate modified by the Soul Siphon talent only? I ask just to know and so I don't go in blind when answering this question for future Warlocks. I would assume that it does, with the 2% heal being given the 20% boost before healing your character.