This is a very intricate 3 phase fight with a lot going on. Fortunately, once again, it is very decent for Windwalkers!
Check out “surviving tabs” for transcendance useage.
Phase 1 is all about tunneling adds while having good reaction time to boss abilities. Use your Touch of Death and cooldowns on the Inquisitor Vethriz when he spawns, you can probably get some Fists of Fury and other cleave hitting the other targets.
Phase 2 will require you to have cooldowns ready to deal with Eye of Gul’dan. On Heroic, you’ll also be killing the Hand of Gul’dan summon. Be sure you use your Storm, Earth, and Fire and other cooldowns when you have several targets up.
As soon as Eye of Gul’dan become Empowered Eye of Gul’dan, you’re going to need Storm, Earth, and Fire casts on each spawn and to nuke these as soon as you can. Don’t forget to re-fixate once Empowered Eye of Gul’dan die!
Phase 3 will mostly be about surviving a few mechanics while keeping the damage on Empowered Eye of Gul’dan really high. As usual, make sure your Transcendence is dropped and you know where it is. Roll and Flying Serpent Kick will carry you through the rest of mechanics.
Phase 1: Make sure you have an eye on the boss because the deadliest mechanic here is the Fel Efflux: if you’re not quick to roll out of it when it’s on melees, you may very well die! Rest is mostly be in the right position.
Phase 2: You can use Tiger’s Lust when being hit by Bonds of Fel. Make sure you’re spread when Eye of Gul’dan are up: as a Monk you can position out of the raid on an outer Eye of Gul’dan with your clones hitting other targets, make use of that! That will also allow you to move out of raid and make sure you’re safe from fire damage when Eye of Gul’dan are up to use your extra action button, Time Dilation, safely.
The best way to trump empowered bonds of fel is to drop transcendance on top of your melee group right before they hit; it will count everyone hit where you land towards spreading the damage and is extremely powerful. This saves a lot on your raid and equates good damage gains, make use of it!
Phase 3: when this phase hits, the boss goes through a short immunity time. Make sure you take this opportunity to hit refresh/drop Transcendence. Dropping this towards the edge might give you an easy way to drop out of the raid with Flames of Sargeras. This is paramount on Heroic difficulty.
If you didn’t, always use Transcendence on boss when going out for a mechanic. You can also use it when he does Storm of the Destroyer so that you can port back to Empowered Eye of Gul’dan if it drops there. Don’t overdo it: you don’t want to die from mispositioning for Black Harvest.
Here you’re gonna recognize aspects of phase 1 and 2 from heroic guldan. Your big focus here is gonna be on Eyes of Guldan as a windwalker. For your first few wipes, I would consider running Rushing Jade Wind. This is not a joke, it will give you crazy good eye damage on every wave. This will be tough on your ressources, so you’re likely to not even use RSK on cooldown during eye downtime.
Once your group get’s used to timings, the eye damage will be smoother, but you’re still likely to use your Storm, Earth, and Fire on these. Due to how important this mechanic is (and timely burst throughout the fight on priority targets) I would highly suggest using Convergence of Fates if you have access to it.
It is paramount that you emphasize the Empowered bonds of Fel cast. You want to drop transcendance right before it hits so that you can teleport back to melee instantly. This will save crazy uptime for you and people soaking bonds, and is a huge asset for windwalkers on this fight. Make use of it!
Touch of Karma is easy to maximize phase 1 and 2 free of risk: Liquid Hellfire hurts like a truck so it’s quite easy to Touch of Karma this. However, this is rarely lethal damage so the healing from Touch of Karma is often wasted there since you’d most likely be topped right after by a large cooldown. Make sure you do the right choice there.
Phase 3 you’re going to have very easy abilities that require Touch of Karma: if you get targeted by Empowered Eye of Gul’dan, you really want to reflect its damage to help nuking it. Otherwise focus on Black Harvest.
About the time dilation extra action button:
Just as for Elisande and Chronomatic Anomaly, this buff makes your cooldowns end faster as well as ticking faster, so you don’t actually win anything from popping it during cooldowns. In theory, therefore, the best way to use it dps wise is to maximize it’s uptime so that things refresh quicker.
However, there is merit to using this on AOE: you do gain way more out of this during high damage phases, aka cleave or AoE. It is, however, hard to use this on Eye of Gul’dan because of the ongoing fire damage. This is also the most beneficial thing to do for the raid.
Therefore, I would encourage you look out for every boss ability and set up this extra action button to be used right after adds spawn and you know you’re not targeted/cleaved on.