life on kill procs off of resummoning hydra's not on the first cast its when you summon more and desummons the old ones counts as killing them
I say them because you get a life on kill proc for each hydra. so if you have 2k life on kill witch is really easy to get you will be healed for 6k hp every second if you are spamming it. by far best self healing in the game.
rep please if you like