Boss Strategy

Introduction
The Assembly of Iron is the fifth boss encounter in Ulduar found in The Assembly of Iron. The encounter consists of Steelbreaker, Runemaster Molgeim, and Stormcaller Brundir. Killing any one of the three will give a soft enrage of +25% damage to the other two and grant them additional abilities (similar to Fathom-Lord Karathress). Killing the second of the trio will grant the last with a final stage apart from their usual abilities which must be dealt with in different tactics.

The hard mode of this fight requires players to kill Steelbreaker last, while the easy mode requires killing him first.

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Understanding The Mobs
Steelbreaker, Molgeim, and Stormcaller Brundir are the dwarfs of The Iron Council. Each time one dies, the others gain another charge of Supercharge: their damage increases by 25% and they gain more abilities. The remaining mobs also heal to full, making a strategy of "burn them all down together" not an option.

Large Dwarf: Steelbreaker
Medium Dwarf: Runemaster Molgeim (technically an Iron Vyrkul)
Small Dwarf: Stormcaller Brundir

Steelbreaker Abilities
With 0 Dwarves down
- Fusion Punch: 100% Weapon damage on his tank. This ability is on a ten second cooldown. If he is in a Rune of Power he will hit far harder, so it's vitally important that he's never standing in them.

- Aura = High Voltage: Deals 1500 nature damage every 3 seconds. When he dies the aura disappears.

With 1 Dwarf down
All the above abilities plus:

- Static Disruption, which deals 7500 nature damage to enemies in an area and increases nature damage taken by 50% for 20 seconds. 12 yard radius. (It's likely this ability will force tank swaps when this fight is done "hard mode" with Steelbreaker dying last.)

With 2 Dwarves down
All the above abilities plus:

- Overwhelming Power: Steelbreaker buffs his current target with this ability, which doubles their damage but kills them when the buff expires. When the player dies in this fashion they explode for 9000 AoE damage in 15 yards.

Electrical Charge: Every time a player dies, Steelbreaker's damage increases by 25% permanently.

Runemaster Molgeim Abilities
With 0 Dwarves Down
- Rune of Power: Runemaster Molgeim casts Rune of Power on a target NPC periodically -- there's a few seconds with no rune and then another appears. It will buff anyone standing in it, including a mob.

With 1 Dwarf down
All of the above abiltities plus:

Runemaster Molgeim gains Rune of Death which does 10000 damage/second (7000 on Normal) starting immediately after cast to everyone in range. It's cast on a target player.

He also periodically casts Shield of Runes on himself: after he takes 50,000 damage, he will increase his dps by 50% for 15 seconds. This ability can be dispelled or spellstolen.

With 2 Dwarves down
All of the above abilities plus:

Runemaster Moldeim gains Rune of Summoning which summons Lightning Elementals with 65k HP. These chase after players and appear to explode and deal damage. Their melee attack is Lightning Blast: deals 14-15.8k nature damage to everyone within 30 yards and kills the elemental in the process.

Stormcaller Brundir Abilities
With 0 Dwarves down
Stormcaller Brundir casts Chain Lightning which chains through the raid. It can be interrupted, and he can have his cast time slowed (e.g. with Curse of Tongues.)

He also emotes that he is Overloading as he's casting a ten-second long spell called Overload; it's vitally important that everyone gets out of range by the time the cast concludes (it deals 25000 nature damage to everyone within 30 yards and knocks them down). Stormcaller is immune to interrupts while casting Overload.

With 1 dwarf down
All of the above abilities plus:

Lightning TendrilsStormcaller Brundir gains Lightning Whirl, which flings AE lightning bolts around and is similar in some ways to the whirlwinding trash before Kael'thas. It's interruptable.

2 dwarves down
All of the above abilities plus:

Stormcaller Brundir gains Lightning Tendrils, where he launches into the air and chases after players, AE'ing everyone in his path.

He also gains Stormshield, which deals 250 damage to attackers and makes him immune to stuns.

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Fight Strategy (Easy Mode Only)

Kill Order:
1. Steelbreaker
2. Molgeim
3. Brundir

Positioning:


Position your raid initially as laid out in the first positioning diagram. This positioning may change slightly depending on which mode of the fight you choose - individual adjustments are described in each section as necessary. The basics of this fight do not require any strange execution from individual raid members - the goal is to kill each Iron in the chosen order while avoiding death from the immense amounts of nature damage present during the fight. Individual assignments are given, again, in the sections devoted to each particular Iron.

If you choose to kill Stormcaller Brundir or Runemaster Molgeim last, you should start by killing Steelbreaker first. Positioning is exactly as given in the diagram: Brundir tank and healer in the back, far from the rest of the raid, and Molgeim on the front left with his tank and healer. The raid positions themselves in the front right third of the room and kills Steelbreaker.

Since Steelbreaker does not yet have any extra abilities, and the raid is out of range of Brundir's Overload, this part of the fight is quite simple. Steelbreaker's tank and his healers should be aware of Fusion Punch spike damage and one paladin or priest healer should be assigned to cleanse the debuff immediately. Since Fusion Punch has a cast time, this should be very simple to do. Also, the Steelbreaker tank should watch for Runes of Power and slide Steelbreaker out of them, allowing the rest of the raid to gain a damage boost from the Rune while denying it to Steelbreaker and his already massive damage output.

*Inexperienced raids should use Heroism / Bloodlust during this phase of the fight to kill Steelbreaker and his High Voltage aura as fast as possible.

After Steelbreaker Is Dead, Killing Molgeim
Now kill Runemaster Molgeim. The entire raid should reposition around Molgeim (these positions are noted with the transparent dots in the diagram) and kill him. At this point, Steelbreaker's tank should move over to help Brundir's tank interrupt his new Lightning Whirl ability while the rest of the raid focuses on Molgeim.



Healing at this point becomes somewhat lighter on the raid because High Voltage is no longer present. Instead, those healers should focus on other key tasks:

1. Shamans should be ready to purge Shield of Runes as soon as Molgeim casts it, or else the shield will be broken by damage, increasing Molgeim's damage by 50%.
2. Other healers should be watching for Rune of Death and help quickly heal players caught in the Rune as they move out of it.

The entire raid needs to be aware of the cooldown (30 seconds) on Rune of Death and move out of the Rune immediately once it is cast. Players who do not immediately begin to move when the Rune appears - it has no cast time to react to - will probably die. Other than this new element, the fight is still quite simple - find Runes of Power if available and DPS Molgeim until he dies.

After Molgeim Is Dead, Killing Brundir
Once Molgeim is dead, the raid can now switch to Brundir, who has gained Lightning Tendrils and lifted off into the air. At this point, Brundir is a lot like the AQ40 boss Battleguard Sartura - he resets his aggro table constantly and is very difficult to control. The raid should position themselves in the south half of the room, while each tank takes up position in the north half of the room. If Brundir turns towards the raid, one of the tanks should immediately Taunt him, turning him back towards the (empty-except-for-tanks) northern portion so his Tendrils will not slaughter the entire raid. Ranged DPS can and should still attack him while he is in flight, and healers should focus on healing anyone who gets caught in front of Brundir and takes Lightning Tendril damage.

Brundir alternates between his hard-to-control Tendrils/Flight phase, where he does not use any other abilities, and being "grounded", when he returns to his normal combinations of Chain Lightning and Lightning Whirl and the fight is - temporarily - similar to Phase 2 again. He is still stunnable and the more often he is stunned, the more difficult it is for him to take off again into his Lightning Tendril flight phase. Rogues, paladins, and protection warriors should chain stuns into Brundir while the raid uses their DPS cooldowns to burn him down. If you have experience with the fight, it's a good idea to save your Bloodlust / Heroism for this portion rather than using it on Steelbreaker or Runemaster Molgeim. Brundir deals very little damage at this point while on the ground, so healing during this phase is quite light.

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Note: Tanking In 10 Man
Tanking is more complicated because most 10 man raids bring only 2 tanks. Here are three options for handling tanking with a 10 person raid group:

1. Bring a hybrid player whose second spec is a tanking spec. They can DPS for most of the raid and then swap into tanking gear for this encounter.
2. Use a DPS spec death knight or DPS warrior to tank Stormcaller Brundir. His damage on Normal mode is incredibly low and both death knights and warriors have the necessary interrupt tools to control his casts.
3. Use one tank (preferably a warrior) to tank both Stormcaller Brundir and Runemaster Molgeim. Since neither hit very hard, one tank can easily take the punishment from both of these Irons on Normal mode.