Soul Siphon
Soul Siphon is a Warlock spell in the WoW Forever client.
Increases the damage done or health drained by your Drain Life, Drain Soul, and Wrack spells by 4% per each of your other Affliction effects active on the target, up to a maximum increase of 12%.
Data from the WoW Forever client, build 1.60.1.70862, extracted .