I have read a lot of the feedback surrounding the one siphon health heal that Warlocks currently have, and how it’s not enough, especially for Demonology Warlocks.
Since Curses are returning as baseline, how about adding a new Curse that does Damage over Time to the mob, and also heals the Demon for some multiplier of the damage done? Essentially doing a heal over time, like a Hunter, but to your demon while also damaging the mob.