Blizzard have set the record straight regarding the Evoker legendary quest drop from the final Aberrus boss, Sarkareth. It’s going to start dropping on all difficulties after the weekly reset in the region where a guild has downed the boss on Mythic difficulty! You can check out the stream of a player that got the item and the quest steps he’s going through right here.
Evoker (Source)
Here’s a bit of info on how this works:
Once Scalecommander Sarkareth has been defeated for the first time on Mythic difficulty, the Cracked Titan Gem item that begins a Legendary weapon questline for Evokers will have a chance to drop from Scalecommander Sarkareth on all difficulties after the weekly reset in the region that he’s been defeated in. The item will be very rare on Raid Finder difficulty (when available) and slightly increases in drop rate with each difficulty.
