During the Patch 1.1.1 Campfire Chat, developer Joe Piepiora confirmed once patch 1.1.1 goes live, starting at level 35, Dungeon Bosses are guaranteed to drop a Legendary item. This also extends to completing Legion Events. Finally, since The Butcher counts as a boss, he too will be guaranteed to drop a Legendary item. FRESH LOOT!
Patch 1.1.1 Unofficial Patch Notes
Before level 35, there is still the chance that a Legendary item will drop from any of the formerly mentioned activities.
