As with every Mythic+ season, there are new rewards for achieving Keystone Master and Keystone Legend. In Season 1, Blizzard added two new achievements and rewards in Umbral Champion and Keystone Myth, but these achievements haven't been seen on the ptr yet.
Season 2 Keystone Master Mount
By achieving 2,000 Mythic+ rating in Season 2 of Mythic+, players will earn the Midnight Keystone Master: Season 2 which awards the Breath of Blight mount!
This works out to be about almost all +7s completed.
Season 2 Keystone Legend Mount
By achieving 3,000 Mythic+ rating in Season 2 of Mythic+, players will earn the Midnight Keystone Legend: Season 2 which awards the Breath of Ruin mount!
In terms of difficulty, this works out to be with all +12s with some +13s.
