This page covers a healer-focused strategy for Mimiron in Ulduar in Wrath of the Lich King. While it's tailored for healers, other roles may also find the information useful. If you have any suggestions or feedback, you can leave a comment below or tweet @PrestonDvorak.

This guide has been updated and maintained based on my own experiences with the encounter, combat log information, and Dungeon Journal information. I'll continue to update it as-needed.

All Stages

• After 15-minutes, goes Berserk, greatly increasing Attack Speed and damage dealt.

Stage One - Leviathan Mk II

This stage begins the encounter and ends when the Leviathan Mk II is killed.

• The tank will be dealing with extra heavy damage over time from Plasma Blast (Plasma Blast on 10-player).
• Stay more than 5-yards away from other players to avoid chaining the damage over time effect from Napalm Shell (Napalm Shell on 10-player). This prefers to target players that are more than 15-yards away from the Leviathan Mk II.
• Stay more than 15-yards away to avoid Shock Blast. Players hit take likely fatal damage.
• Avoid the Proximity Mines laid in a circle around the Leviathan Mk II. Triggering a mine deals moderate damage to all players within 3-yards with Explosion.

Stage Two - VX-001

This stage begins when the Leviathan Mk II is killed and ends when the VX-001 is killed.

• The VX-001 is stationary in the center of the room.
• Avoid the impact location of Rocket Strike, targeted at a random player's location. Players hit take fatal damage.
• Every 60-seconds, during Spinning Up, don't stand in front to avoid the P3Wx2 Laser Barrage as the boss slowly rotates.
• Deals light damage to random players with Rapid Burst.
• Deals light damage over time to all players with Heat Wave for the duration of the stage.

Stage Three - Aerial Command Unit

This stage begins when the VX-001 is killed and ends when the Aerial Command Unit is killed.

• Aerial Command Unit
  • Often tanked by a ranged DPS.
  • Out of range of melee attacks until pulled to the ground with a Magnetic Core from an Assault Bot, detailed below.
  • The tank will be dealing with light to moderate damage from Plasma Ball.
• Every 30-seconds, an Assault Bot spawns from a construction pad somewhere in the room.
  • Assault Bot
    • Dispel Magnetic Field (magic) to remove the increased damage taken and Root effect.
    • Upon death, a Magnetic Core can be looted from its body.
      • The player who loots it should use it and target the reticle underneath the Aerial Command Unit to pull it to the ground with Magnetic Core and greatly increase it's damage taken.
• Frequently spawns other lesser enemies from construction pads around the room.
  • Bomb Bot
    • Susceptible to most Stun, Snare, and other crowd control effects.
    • Upon reaching a player, deals moderate damage to all players within 5-yards with Bomb Bot.
  • Junk Bot
    • The tanks will be dealing with light melee damage.

Stage Four - V0-L7R-0N

This stage begins when the Aerial Command Unit is killed and ends when the three units from the previous stages, which combine to make up V0-L7R-0N, are killed.

• The tank will be dealing with extra heavy damage over time from Plasma Blast.
• Avoid the Proximity Mines laid in a circle around the Leviathan Mk II. Triggering a mine deals moderate damage to all players within 3-yards with Explosion.
• Every 60-seconds, during Spinning Up, don't stand in front of the VX-001 to avoid the P3Wx2 Laser Barrage as the boss slowly rotates.
• Deals moderate damage to random players with Plasma Ball.
• Deals light damage to swaths of players with Hand Pulse.
• When a unit is killed, it begins casting Self Repair, healing back to 50% health if the other two units aren't killed before the cast finishes.

Hardmode is activated by pushing the Big Red Button at the back of the room labeled DO NOT PUSH THIS BUTTON.

• All Stages
  • All enemies gain Emergency Mode, increasing damage dealt and maximum health.
  • Avoid the locations of Flames, which slowly spread towards the nearest player(s).
  • Now goes Berserk after 10-minutes.
• Stage One - Leviathan Mk II
  
  • Avoid the impact location of Flame Suppressant. Players hit gain a reduced casting speed effect. This also clears any Flames it hits.
• Stage Two - VX-001
  • Stay more than 30-yards away from the Frost Bomb, targeted at a random location in the room. Player hit take likely fatal damage, and are knocked back if they survive.
• Stage Three - Aerial Command Unit
  • Frequently spawns Emergency Fire Bots from construction pads around the room.
    • Emergency Fire Bot
      • Stay more than 10-yards away to avoid the Silence effect from Deafening Siren.
      • Don't stand in front as it moves around to use Water Spray on Flames.
• Stage Four - V0-L7R-0N
  • Stay more than 30-yards away from the Frost Bomb, targeted at a random location in the room. Player hit take likely fatal damage, and are knocked back if they survive.

Quick Notes, All Difficulties

The notes below mostly pertain to progression difficulty, meaning if you out-gear the difficulty you're on or use extra healers they may not apply.

• Use Major Cooldowns
  • during stage two and stage three
• Use Minor Cooldowns
  • as-needed to keep the tank alive during Plasma Blast
  • as-needed in stages two and three
• Pre-heal Before (mainly for heal over time classes)
  • stage two and three
  • then, keep heal over time effects active throughout those stages to counter the persistent damage
• Other things to watch for
  • Healing required is generally low during stage three, which is a good time to conserve mana.

Major

• Magnetic Field (dispel, magic) should be dispelled immediately.
• Plasma Blast (Plasma Blast on 10-player) causes the tank to need additional moderate healing over time.

Minor

• Napalm Shell (Napalm Shell on 10-player) causes players to need additional light healing over time.