When quizzed as to how boss battles will play out in Diablo III and whether players can expect to see the same predictable boss fights as they did in Diablo II, Blizzard community manager Bashiok confirmed that the game would feature unique boss fights and provided an example of one such battle.
"I hope you're not calling that an interesting fight, or saying Diablo II was replayable because it had no mechanics beyond the boss' abilities.
In Diablo III we want at least some boss fights that aren't defined simply by having a creature with more health, unique art, and more powerful abilities. We want there to be something more to them, tell a story, have more unique mechanics that make sense for the boss.
As far as the original topic, when health globes could be delivered during a boss fight, there's really no limit for how they could be delivered. Take the King Leoric fight, they were delivered through creatures that he summoned, normal skeletons. Every boss could essentially have the same thing, normal enemies around him that can be killed for the potential at getting a health globe drop. Or, you could have something more interesting ... like a boss that does a special attack that has the ability to break open some large corpse storage tanks that are in his lair. The player has to lead the boss to the tank and try to invoke the special attack so he'll break the tank open, which unleashes some health globes. You could even treat the tank (code-wise) as a normal creature, meaning abilities and items could augment the number that drop and amount they heal, etc. giving some control to the individual player. If you don't need the health you can ignore the mechanic, but it could be a way for players to try to game the boss and make sure they can survive the fight. Totally hypothetical, we don't have a fight that resembles what I described, but it's a possible delivery system.
I disagree that having bosses that do something more than simply cast the spells they're given to cast kills replayability."
