Yeah, at least from that old gameplay video (d3), some spell casters show like a ping on the map prior to casting their spells. Or was it so? Can't remember.
The skeleton king, was he then like forced to spawn mobs so the player can get health orbs, or does he give health orbs at certain Hit Point levels? Like say, if the player manages to damage him up to 3/4 health, poop comes health orbs.