I Choose You, Steelbreaker (10 player)

A reference to Pokemon of course.

Done this with guildies on 25/05/09

rather easy hardmode achievement with correct setups.
[[2 Tanks / 2 Healers / 6 Dps]] or [[2 Tanks / 3 Healers / 5 Dps]]

both will work depending on your healer/dps capability
And also it is highly suggested NOT to take 3 tanks.
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-------Preparations------
1) Having a Hunter/Shammy to use/drop Aspect of the Wild/Nature Resistance Totem will help in overall damage reduction taken by Steelbreakers High Voltage and Fusion Punch.
2) Having a Spriest/Retadin for Vampiric Embrace/Judgement of Light will help ALOT
3)Dispels on Steelbreaker tank is a 'MUST' i find retadins do best job on doing this since they can make easy macros like /cast [target='Main Tank's Name'] Cleanse and just spam it when they see Steelbreaker casting Fusion Punch
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-------Tactics------
Kill Order => Runemaster Molgeim > Stormcaller Brundir > Steelbreaker

MT on Runemaster Molgeim + Steelbreaker
OT on Stormcaller Brundir

Phase 1
MT should make sure he focus on either Runemaster Molgeim or Steelbreaker he will need to watch out for Fusion Punch and Rune of Power. When Runemaster Molgeim Casts Rune of Power, the MT should see if it's targetting either Runemaster Molgeim or Steelbreaker, if so, he should move quickly away from the spot.
OT should just interrupt Stormcaller Brundir as much as he/she feels like since it only does Chain Lightning and Overload.
There should be 1 dedicated healer on MT, 1/2 Raid healers who off heal MT/OT whenever needed.

Phase 2
Once Runemaster Molgeim is dead, all Dps should spread out, and kill Stormcaller Brundir, very easy, just run out of overload and keep at least 1 interrupter on Lightning Whirl, if you got a DK, he could Anti-Magic Shell every Overload to stay in range for interruption after the explosion. Just don't have all interrupter waste their kicks/interrupts on 1 chain lightning and wipe from the Whirl.

Phase 3
Prior to entering this phase, the 'worse geared' of the 2 tanks should tank the boss first, which will normally be OT.
Before you kill Stormcaller Brundir, MAKE SURE even if you have to stop dps completely, that the OT does not have Static Disruption debuff. This debuff, well with Fusion Punch, can one shot any tanks. Once OT grabs the boss, it will be dps race, Use Bloodlust / Heroism and just nuke the boss until OT dies from Meltdown. All Melee should be watching over the tanks debuff to run away when OT dies, since explosion could easily kill you. When a OT dies, the boss will regain about 20% health and get a 25% boost damage (Along with Superchargex2) the MT may need CDs to survive this phase. Steelbreaker will need to be roughly 20% before the OT dies or you will need to re-arrange your group in order to increase overall damage.

The above Tactic is to prevent Rune of Power + Fusion Punch death that can occur if Stormcaller Brundir and prevent the AoE damage from Rune of Death
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Zxin - Burning Blade EU

Killing a boss of the Iron Council Supercharges the remaining bosses, healing them to full, increasing their damage and giving them new abilities. To get this achievement, Steelbreaker must be killed last. Since his abilities are most dangerous, this is considered to be the hard mode of the encounter.

Steelbreaker starts off with the High Voltage and Fusion Punch abilities.
When 1 other boss is killed, he can cast Static Disruption, an AoE and nature vulnerability spell.
When both other bosses are killed, he can debuff a player with Overwhelming Power, increasing that players damage but causing a Meltdown after 1 minute, killing that player. Once both other bosses are killed, Steelbreaker also gains a stacking +25% damage buff for each player he killed (including Meltdown casualties).