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Thorim is a very interesting fight in the Ulduar raid instance.  Players should be at least aware of Thorim as he is involved in several long quest chains in the Storm Peaks zone in Northrend.  The fight against Thorim is a two phase fight, with the group being divided for the first phase.  Each group in the first phase has a separate challenge to complete before being reunited in the second phase, where they must defeat Thorim.


10 Person Raid: 2,900,000 health
25 Person Raid: 14,600,000 health

Additional Creatures in the Fight (Adds)

There are several different Adds involved in the Thorim fight.  The first ones are found as you enter the arena, they are a giant Jormungar and a group of Mercenaries.  The only real ability of note is the Dark Rune Acolyte which is described below.

Once the initial group of Adds are defeated, the arena team and hallway team split off and each have to deal with a mix of creatures that include two mini-bosses in the hallway, Dark Rune Acolytes, Champions, Commoners, Warbringers, as well as Iron Ring Guards.

Hallway Adds

Dark Rune Thunderer – The Thunder hits players with a lightning shock that also increases nature damage taken by 40% for the next 20 seconds. The damage debuff stacks, therefore they need to be dispatched quickly.

Dark Rune Acolyte – The Acolyte needs to be a priority target as it can cast a huge 100,000 health heal on other Dark Rune targets, making the fight last longer than it needs to.  The heal is a 2 second cast and can be interrupted.  While the Acolyte also has a smite, the heal is the primary concern.

Iron Ring Guard – The Guard is a melee based attacker whose main attack is a nasty impale.  The impale causes bleed damage until the player is healed back to near full health (over 90%), until then they suffer roughly 1500 damage per tick.

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Ancient Rune Giant

Ancient Rune Giant – The Rune Giant is the first mini boss that players in the hallway face.  It has charge and smash attacks as well as a runic barrier ability.  The charge hits players for up to 8,000 damage (6,000 in 10 player raids) and knocks them back, while the smash hits anyone unlucky enough to be in his frontal arc for up to 40,000 physical damage (30,000 in 10 player raids).  His Runic Barrier reduces incoming damage by half and inflicts roughly 2,000 damage per hit back onto the attacker.

Runic Colossus – The Colossus is the second mini boss that players face in the hallway.  Its main abilities are a stomp and a rune attack.  The stomp knocks everyone within 10 yards away while also inflicting roughly 15,000 damage (10,000 in 10 player raids). The runic detonation attack places runes on that ground that will cause players in them to freeze in place and then explodes 5 seconds later.  The explosion does roughly 13,000 damage (10,000 in 10 player raids) to the target and everyone nearby.

Arena Adds

Dark Rune Champion – The Champion is a fairly standard Warrior that has Charge, Mortal Strike, and Whirlwind attacks.  Melee needs to stay clear when he whirlwinds, and the tank will require additional healing after a mortal strike since it reduces healing received by 50% for 5 seconds.

Dark Rune Commoner – Commoners are not much more than an annoyance as they have low health and do not inflict much damage.  They do have a stacking debuff that lowers your damage output by 3% for 20 seconds, however if dealt with quickly it rarely gets a chance to build up on the tank or a melee player.

Dark Rune Warbringer – The Warbringer is the number one priority while alive in the arena due to his Aura of Celerity, although he also has a Runic Strike.  His aura increases all other Dark Rune adds in the arena to gain a 20% increase to melee, ranged, and casting speeds.  Since this stacks with additional Warbringers, allowing more than one to stay alive at any given time is asking for trouble.

Thorim’s Abilities

Chain Lightning – Thorim casts a chain lightning spell that hits for roughly 5,000 nature damage (4,000 in 10 player raids).  Once a player is hit, the lightning will arc to up to 3 additional nearby players inflicting escalating damage to them.

Lightning Charge – Occasionally Thorim will absorb power from one of the pillars around the arena.  This is shown by lightning flowing on the ground for a few seconds from one of the pillars.  After the lightning on the ground, which serves as a warning to players, lightning arcs towards Thorim from that section of the room.  It strikes everyone in its way with roughly 20,000 damage (15,000 in 10 player raids).  The way to avoid this is to simply watch for the lightning charge on the ground and move to the opposite side of Thorim when you see it. When Thorim does this he gains a stacking buff called Lightning Charge that increases his attack speed and damage by 15% and the nature damage he causes by 10%.

Stormhammer – Thorim will throw his hammer at a random player in the arena during the first phase of this fight.  It hits for only a few thousand damage, however it also knocks the player back and stuns them for a 3 seconds.  In addition it will cause a silence effect on everyone within 10 yards of the target that lasts

Unbalancing Strike – This attack hits the tank for 200% of Thorim’s normal attack damage and reduces their defense skill by 200 for 15 seconds.  This means that the tank will be susceptible to critical strikes for that period of time.



This fight is broken down into several parts, and while it could be called a three phase fight, technically, only two phases really matter.  When you first enter the arena you will be faced with a group of guards fighting a giant Jormungar. This could be called phase one, however it is so easy and simple that players generally don’t consider it as anything but the start of the event.  Simply target the healer in the group first, kill him, and then mop up the rest of them.

Once the initial group in the arena has been defeated, Thorim will start to talk and then Sif will prompt him to action.  At this point the group needs to split into two teams, a team to stay in the arena, and a team to enter the hallway.  The hallway group will need to fight their way up to Thorim and force him to enter the arena, while the arena team survives through unending waves or Dark Rune Dwarves.  The Hallway team operates the leaver to open the gate and leaves the arena team behind.

[protip] The Hallway is fairly simple, especially in 10 player raids.  This means that you really should stack the Arena team.  Most of the time a single healer, tank, and ranged DPS can handle the hallway in 10 player raids, and a group of 5 is more than enough in 25 player raids. Generally the raid will live or die through the arena teams ability to survive.[/protip]

Phase 1

The Hallway Team must advance down the hallway and reach Thorim within 5 minutes or he will trigger a lightning shock that rolls down the hall killing everyone.  The hallway team needs to deal with three groups before reaching the first mini-boss, all while dodging to the left or right side of the hall as waves of lightning are sent down random sides.  Once you engage the first mini-boss you need to inflict as much damage as quickly as possible before it puts up its runic barrier that reduces damage and inflicts damage back. 

Once past the first mini-boss the hallway team will see two groups of two adds on the stairs that must be engaged, as well as more that spawn from the top of the stairs.  The adds will continue to spawn until the second mini-boss is engaged.  Once engaged, the tank should stay in line of sight of the healer at the top of the stairs, while ensuring colossus can not actually see the healer to place runes on them.  Once the colossus has been defeated, engage Thorim and he will leap into the arena below, follow him to start phase 2.

While the hallway team is making their way to Thorim, the arena team’s job is to simply survive.  While in the arena players must deal with waves of Dark Rune Dwarves and overcharged orbs.  The orbs are found on the towers around the perimeter of the arena and will randomly start doing damage to everyone near them.  To minimize the damage inflicted to players the group should stay near the center of the room, and when venturing out of the circle in the center simply look to the towers nearby and check for a glowing effect. If the tower there is glowing, simply get back to the center of the room or the opposite side.

To deal with the Dark Rune Dwarves that spawn, the tank needs to gain agro and then DPS players can kill them.  Hunters and Rogues can help with their threat misdirection abilities, while healers should ensure they remain close to the tanks so that they can pull dwarves off of them easily.  The adds need to be DPSed down with the Warbringers as the highest priority followed by Champions and lastly any remaining dwarves.  The warbringers provide damage boosts to everything else in the room and therefore are very dangerous.  Once they are down the Champion’s whirlwinds cause the most issues.  The commoners can be AoEd down any time there is time to spare.  While this may sound easy, don’t expect it to be, you will not have much free time as the fight get progressively harder and the adds come faster and in bigger groups.

Continue dealing with the Dwarves until the hallway team forces Thorim to enter the arena.

Phase 2

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Thorim Waiting for You

After the hectic action of phase 1 suffered by the arena team, phase 2 is almost anti-climactic.  Very simply, the phase can be described by avoiding the lightning charges and tanks trading threat whenever they are hit by an Unbalancing Strike.  This is a DPS race though, so don’t take your time. Every time Thorim uses lightning charge he will get stronger.  Realistically, you have about 12 buffs before the fight becomes too hard to heal through.

Whenever lighting charge is being cast, players need to watch for the charge on the ground and move to the opposite side of Thorim.  When he completes channeling the ability lighting will come from about 1/5th of the room towards him in a pie shape.  It stops at Thorim, but anything between the lightning’s spawn point and Thorim will take large amounts of damage.

Due to Unbalancing Strikes ability to make tanks crittable, they need to trade threat as quickly as possible when they are hit by it.  If they suffer another hit while under its effects, they could be critically hit and one-shotted.

Assuming everyone in the raid avoids the lightning and the tanks trade agro back and forth, the second phase is over relatively quickly.  Thorim will stop fighting at roughly 1% health and you can gain access to his loot from the chest that will spawn.

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Last Updated: Mar 13, 2016

About The Author

Byron 1
Byron has been playing and writing about World of Warcraft for the past ten years. He also plays pretty much ever other Blizzard game, currently focusing on Heroes of the Storm and Hearthstone, while still finding time to jump into Diablo III with his son.


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