I want to open up discussion of Mimiron now, before we start working on him in earnest. Here's a run-down of the phases and the abilities (copied from WoWhead)

Phase 1
Leviathan MK II

1. Proximity Mines - Drops 8-10 Proximity Mines around MK II. After a small arming time, the mines will inflict 12,000 Fire damage to anyone who walks over them.

2. Napalm Shell - Inflicts 7,540 to 8,460 (Heroic: 9,425 to 10,575) Fire damage instantly and an additional 4,000 (Heroic: 6,000) every 1 second, for 8 seconds. This spell will always attempt to hit targets farther than 15 yards of MK II.

3. Plasma Blast - After a 3-second cast, MK II will channel a stream of plasma for 6 seconds, inflicting 20,000 (Heroic: 30,000) irresistible Fire damage every 1 second to his target.

4. Shock Blast - After a 4-second cast, MK II will inflict 100,000 Nature damage to all enemies within 15 yards of him. Used soon after a Plasma Blast.

Phase 2
VX-001

1. Rapid Burst - Inflicts 1,414 to 1,586 (Heroic: 1,885 to 2,115) Spellfire damage to a random target every half-second for 3 seconds.

2. P3Wx2 Laser Barrage - After a 4-second cast, VX-001 will shoot a laser in a random direction and spin slowly. The laser will inflict 20,000 Fire damage every 0.25 seconds, and will last 10 seconds.

3. Rocket Strike - VX-001 will fire a rocket that will travel to a location underneath one of the players. Reaching the location, it will inflict 5 million Fire damage to everyone in 3 yards radius.

4. Heat Wave - Inflicts 1,885 to 2,115 (Heroic: 2,828 to 3,172) Fire damage instantly and an additional 2,000 (Heroic: 3,000) Fire damage to the whole raid every 1 second, for 5 seconds.

Phase 3
Aerial Command Unit

1. Plasma Ball - Inflicts 9,425 to 10,575 (Heroic: 14,138 to 15,862) Spellfire damage to its current target.

2. Summon Adds - ACU will periodically summon Assault Bots, Bomb Bots, and Junk Bots.

3. Assault Bots - Cast Magnetic Field on their target, locking it in place and causing it to take 30% more damage for 6 seconds. When killed, Assault Bots will drop Magnetic Core, which can be used bring ACU to the ground, disable it and cause it to take 50% more damage for a few seconds. The Magnetic Core has to be used underneath the ACU. Assault Bots spawn off red beams.

4. Bomb Bots - Walk aimlessly and explode when they die, inflicting 9,425 to 10,575 damage. They spawn underneath ACU, after a short cast.

5. Junk Bots - Low on health and with weak damage, Junk Bots don't do anything special. They spawn off green beams.

Phase 4
V0-L7R-0N

1. Proximity Mines - Drops 8-10 Proximity Mines around V0-L7R-0N's MK II. After a small arming time, the mines will inflict 12,000 Fire damage to anyone who walks over them.

2. Shock Blast - After a 4-second cast, V0-L7R-0N's MK II will inflict 100,000 Nature damage to all enemies within 15 yards of him.

3. Hand Pulse - Inflicts 4,242 to 4,758 (Heroic: 6,598 to 7,402) Spellfire damage to a random target and all enemies between the caster and the target.

4. P3Wx2 Laser Barrage - After a 4-second cast, V0-L7R-0N's VX-001 will shoot a laser in a random direction and spin slowly. The laser will inflict 20,000 Fire damage every 0.25 seconds, and will last 10 seconds.

5. Rocket Strike - V0-L7R-0N's VX-001 will fire two rockets that will travel to a location underneath two of the players. Reaching the location, they will inflict 5 million Fire damage to everyone in 3 yards radius. During all the duration of the spell, the MK II component is stunned.

6. Plasma Ball - Inflicts 9,425 to 10,575 (Heroic: 14,138 to 15,862) Spellfire damage to its current target.

.
.
.

I'd especially like to hear from the people who worked on him on 10-man for 3 hours. What were some things that tripped you up, what tips and tricks do you have to share, etc.

Mines were an issue for melee, that have to be very aware of their exit strategy for shock blast. The cast time is short so the best thing would be to line up with a gap behind you, turn your camera 180 degress, and when he starts to cast, hit both mouse buttons and split (keyboard turn=fail). There is potential for the tank to get one shotted in this phase, and melee can die very easily to mines or the shock (if you eat either one you're dead), fortunately these are both very easy to avoid and there is no excuse for them to die to either. I think marking one very aware melee and having the others stack on them might be helpful initially. The tank should also try and keep him centrally located so the mines stay contained in one area and we don't have overlapping circles of them in too wide an area.

In phase 2 moving as little as possible I think is the best. Stack in 2 or 3 groups and when someone in that group is targeted, just eat it and heal through it. The ranged groups should be at a range so that hunters can stay with the group since I seem to remember Kou standing alone and taking the brunt of a lot of his attacks. Once he picks a direction he stays there, so if the melee gets targeted they can simply run through him to the other side, but they shouldn't be standing in line with one of the ranged groups at any time, similar to the first boss in the arachnid quarter. When he spins up just run ahead of the beam or stack on his ass. Ranged dps could move the same way melee does, but maxing dps and getting through this as fast as possible is better I think. Its too complicated getting everyone to restack after a Rapid Burst.

Phase 3 seemed to be about controlling adds, tanks maintaining threat. One ranged dps will need to tank him but when asti did it, healing him wasn't terribly difficult. The tanks taking adds seem to take more damage. Having some ranged dps on bomb bot duty is important, classes that can one shot them. Melee should grab the cores and have a mic or a macro to call out when he's coming down.

Phase 1 was single target healing intensive, phase 2 was raid healing intensive (I don't think there is really a tank), phase 3 eases up on both quite a bit and actually allows for some mana regen.

While we saw phase 4, I don't remember getting a handle on it enough to make any suggestions other than timing to get all 3 parts down at once. Just need to keep people from panicking.

It is a really fun encounter and some how not a drudgery like 3D and the like.

A definite key is staying alive, as always trying tp pump out that extra little dps and staying in can result in a death and isn't worth it for sure. The first time he does the shock wave i think a lot of us died the first time because of not being totally sure what to watch for, it's obvious though, lots of electricity starts running all over the flame leviathan. Turn and run out your predetermined path immediately, the blast radius is gigantic, so don't run across the room or anything but definitely get away... and backpeddaling doesn't work. Phase one is definitely about just staying alive.

phase 4 our healers have to remember that a range dps is still a tank

i died quickly in phase 4 one time, but the phase 3 range tank will tank in phase 4 as well

Ottar - if you're talking about the rockets in phase 2, I don't think anyone is going to be able to heal through 5 million damage.

no I was talking about the rapid fire

I did a quick search, in 10s you can stack up in 2 groups but in 25s you need more, its still suggested that you stack but in groups of 3-4; one healer and several dps, in a circle around him. The melee stay in between the ranged groups so the cone of his attack doesn't hit the ranged.