Finally, a tank spec! Brewmasters are getting a rework in Legion, focusing, appropriately enough, a lot more on Brews and less on dodging and absorbing absurd amounts of damage. As always with these breakdowns, remember that we're still in Alpha (though it's a blurry line between Alphas and Betas these days) and thus all these things could change through iterations on the design before they go live.
Much like the other Tank/Melee/Healer hybrid, the Paladin, the big secondary resource for the class is now going only to the dps spec, though in the case of Monks, this is a bit more radical because unlike Paladins, Monks have always had another resource - Chi. No longer!
Brewmasters are still built around the use of Stagger as a mechanic, but other things are being pushed into the background while that aspect of the spec and the two main brews that interact with it are getting moved to the forefront.
Let's talk active mitigation first!
Ironskin Brew and Purifying Brew share 3 charges and a 20-second recharge. Purifying Brew works just as it always did (but with no resource cost other than these charges,) purging your Stagger damage. Ironskin Brew increases your Stagger amount by 60% for 6 seconds. So clearly, Ironskin makes Purifying a lot better.
Fortifying Brew remains a major defensive cooldown, but I believe the big change for all tanks is that these major cooldowns also count as active mitigation for bosses like Mannoroth.
Tiger Palm is the new Jab, costing 50 Energy and reducing the cooldown on your Brews by 1 second (not sure if this counts Forifying.)
Keg Smash looks largely the same, with a 40 Energy cost and an 8 second cooldown, and also reduces the cooldown of your brews by 4 seconds. It still includes the slow.
Blackout Strike replaces Blackout Kick (presumably because we'll have a staff instead of fist weapons.) It has no cost and a 3 second cooldown, and looks like it will be mainly for threat and damage.
Breath of Fire is on a 15 second cooldown (though it also says it still costs Chi, which means this could be out of date) and much like Blackout Strike, will probably be mainly for threat and damage. It also burns the target as a DoT if Keg Smash is affecting the target, just as it does now.
Zen Meditation is a major cooldown that reduces all damage taken by 90% for 8 seconds, but appears to be channeled.
Notable absence is Spinning Crane Kick, but presumably between Keg Smash and Breath of Fire, we'll have enough AoE to hold threat. Also missing is Dizzying Haze, which I get is slightly redundant with Keg Smash, but was nice for pulling.
Mastery: Elusive Brawler now makes every hit you receive increase your dodge chance, stacking up until you successfully dodge.
As always, we're setting aside talents and artifact traits for now to get the raw, bare-bones rotation.
1. Purifying Brew if Stagger damage is Medium or higher.
2. Ironskin Brew
1. Keg Smash
2. Tiger Palm
3. Breath of Fire (depending on what kind of cooldown it has, and if it winds up being shared with Blackout Strike)
4. Blackout Strike
So yes, Guard and Elusive Brew are gone, but they're clearly focusing on making Stagger a much more significant part of Brewmaster tanking, which frees up some design space for other tanks (like Vengeance.) The loss of Guard in particular might feel like it opens you up to a lot more spiky damage, but the massive 60% Stagger (on top of 6% baseline, and half the total amount for spells) from Ironskin should help a lot in that regard.