Despite having a bumpy night the night we killed him, I really do like this fight. I think the dynamic is pretty clever, and who doesn’t like killing big, angry monsters?
The Trash is complicated. CC everything you can. We usually have 1-3 sheeps, a hex, a banish, a hunter trap or two, and a couple of tanks. All I can tell you is to mark them, control them, and kill them while keeping most of the raid alive. There will be three faceless monsters you’ll fight before facing Vezax; one on the way in and two in his room. (Note: the two in his room begin patting as you kill packs of trash, so kill a pack -> kill the ugly thing). The faceless monsters spawn a voidwalker during the fight, and while the voidwalker is up, they are immune to all damage, so kill the voidwalker and get back on the uglies.
The Fight
Each role has a different set of rules for this fight, but it’s important that everyone be aware of everything else that could be going on at the same time because you never know where you could find yourself.
The things that everyone really needs to know about is 1) mana regen doesn’t work on this fight. Potions don’t work (some say they’ve seen it; we guess it’s a 50/50, so plan for them not to work and then you’ll be extra pleased if it does), Innervate doesn’t work, talents don’t work, Wisdom doesn’t work…you get the idea. This applies to everyone in the raid throughout the encounter, but there are ways to deal with it and they differ from role to role. 2) Mark of the Faceless is a debuff that doesn’t hurt the person carrying it but causes the boss to basically drain life (or “life leech,” as DBM calls it) from anyone around you, so if you get this debuff, run into a corner all by your lonesome until you see it tick off.
There are two kinds of aides throughout the fight. One of them is the Shadow Crash, which increases haste and damage but decreases healing done (so healers should certainly avoid it). The other is Saronite Vapors, which replace mana at the cost of life. I’ve explained them in greater detail below.

You'll feel like an oomkin again.
The Ranged
Let’s face it, we’re pretty mana dependent, and for that reason we have Shadow Crashes. First of all, turn your chat bubbles on, as DBM causes people with incoming Crashes to call it out and chat bubbles help tremendously. Shadow Crashes are painful damage / knockback shadow “bombs” that Vezax throws at anyone outside of melee range. For this reason, if someone has an incoming Crash, move away from them.
However, once the Crash lands it leaves a big, black puddle on the floor that increases your damage and haste by…a lot. The only time you should cast is when you are standing in one of these Shadow Crashes; anything else is a waste of mana.
We usually have one or two groups of ranged standing together to get the most benefit from the Shadow Crashes, but this means that each individual is much more responsible for getting away from other people when they get Mark of the Faceless. So pay attention and make love to your corner when you get it.
The other responsibility ranged has is to kill Saronite Vapors for healers. These spawn and float around the room. They are not hostile, but they are a limited resource. You only get so many during the fight (I think it’s 7 or 8), so don’t be in a rush to kill them. We have 1 ranged (generally a hunter) assigned to this task. When a healer calls for a vapor, he kills it and calls the location on vent in relation to the boss. This allows healers to quickly get to vapors and get their mana back.
The Healers
I can’t give you an in depth understanding of the healers because…well, I’m not one anymore. I can tell you that they all stack under Vezax’s butt and melee him. This is a) so they don’t get Shadow Crashes (which decrease healing), b) so they get mana back from a pally’s Judgement of Wisdom, which apparently works, and c) because it gives them a thrill. Our healers are on a rotation, although you’d have to pester our buddy Kuzgar to understand it. Basically, only 2 healers are actually healing at a time. The rest are either meleeing Vezax or getting into Saronite Vapors. We have one healer who is both a backup healer and a heal-the-healers-in-the-vapors healer. They rotate in and out of healing and vapors as needed. While dps can occasionally stand in vapors to regen mana, I do not recommend it. If a dps is standing in the vapors, it should be because you’re absolutely at the bottom of your mana well and your dps is desperately needed. DPS standing in vapors lose health, but more importantly, risk dropping a crash on a vapor, and that’s just not good strategery. Leave it for the healers, please.
The Tank & Melee
I know, I’m just giving everyone special love today. The only thing I want to mention here (since I am not a tank, and don’t plan on speccing bear or kitty) is that Vezax does an ability called Searing Flames. It’s channeled and it’s very obvious, as he has big glowing orbs spinning around him while he’s doing it. Not interrupting it will usually cause a wipe, and this mainly falls to melee since casters are desperate to conserve mana. The other ability to worry about is Surge of Darkness, which causes him to hit harder and faster. Some strats call for the tank to kite during Surge, but we let ours stand where he is (isn’t he lucky?) and we blow cooldowns to keep him alive. Between him, the pallies, and the discipline priest, this is usually not a problem.
As surprising as this may sound if you’ve never encountered him before, this is actually a pretty easy fight once everyone understands what they’re doing. Explaining it, on the other hand, is a challenge of its own.
Good luck!