Keystone Master is much easier to acquire in War Within with the new score system!
With the new affix system, there's a new score system in place for War Within. While we don't know the specifics, we can estimate what level keystone you need to get Keystone Master and Keystone Hero.
The War Within Keystone Master: Season One is a popular goal for many WoW players, with it awarding a mount! For Season 1, players must achieve 2,000 Mythic+ score to earn the Diamond Mechsuit mount!
When you get Keystone Master, you also get The War Within Season 1: Spelunker Supreme if you haven't already gotten it. This awards Mark of the Spelunker Supreme in your mail — a free Heroic Tier Piece!
For players that haven't killed Heroic Ansurek or reached 1,600 PvP, this is a great way to get a free Heroic tier piece!
The War Within Keystone Hero: Season One is the next step above KSM, requiring 2,500 score and awards Luminous Nerubian Catalyst Stone which allows you to unlock new cosmetics on your tier gear!