Libram of Discovery

Engrave your cloak with the Soul Siphon rune: Causes your Drain Soul to to deal damage 3 times faster and increases the amount drained by your Drain Life and Drain Soul spells by an additional 6% for each of your Warlock Shadow effects afflicting the target, up to a maximum of 18% additional effect. When Drain Soul is cast on a target below 20% health, it instead gains 50% per effect, up to a maximum of 150%. In addition, your Drain Soul can now trigger your Nightfall talent.