From now until the next weekly reset (September 15th (NA)/16th (EU)), the Midnight Dungeon Event is live, giving players a guaranteed piece of Hero track gear!
Head to Archmage Aethas Sunreaver and pick up the Emissary of War weekly quest to complete 4 dungeons on Mythic difficulty. Once completed, you will be rewarded with a Heroic 
Cache of Amani Treasures, containing a piece of Venomous Abyss loot ranging from Item Level 305 to 315!
During this event, the final boss of each Midnight dungeon on Normal, Heroic, and Mythic 0 will drop an extra item when defeated. This makes the event a particularly great opportunity for any players/alts looking to gear up or fill missing slots.
However, it is worth noting that the extra loot drops do not apply to Mythic+ dungeons, but Mythic+ dungeons will count towards the weekly quest.
Still, with the weekly quest and bonus drops from lower difficulties, there are plenty of reasons to jump into some Midnight dungeons before the event ends!
