Two decades have passed since the demonic denizens, Diablo, Mephisto, and Baal, wandered the world of Sanctuary in a vicious rampage to shackle humanity into unholy slavery. Yet for those who battled the Prime Evils directly, the memory fades slowly and the wounds of the soul still burn.
what are they doing ....is it ritual??
It's some kind of Witch Doctor spell/skill. By the looks if it, I think he drains their life and heals himself.