This article is about the original 40-man version of Thaddius introduced in Patch 1.11. For the 10 and 25-man versions of the raid boss introduced in Wrath of the Lich King, see Thaddius.
Image of Thaddius
Race Flesh titan (Undead)
Level ?? Boss
Reaction Alliance Horde
Location Abomination Wing, Naxxramas
Naxxramas (Classic)
Spider Wing

Grand Widow Faerlina


Abomination Wing



Plague Wing

Noth the Plaguebringer
Heigan the Unclean


Deathknight Wing

Instructor Razuvious
Gothik the Harvester
The Four Horsemen


The Four Horsemen

Lady Blaumeux
Thane Korth'azz
Highlord Mograine
Sir Zeliek


Frostwyrm Lair



Other NPCs

Tarsis Kir-Moldir
Master Craftsman Omarion
Mr. Bigglesworth



Thaddius is the fourth and final boss of the abomination wing in Naxxramas. The theme of this boss is similar to that of Frankenstein's Monster, creating something akin to an abomination in that it is sewn together of human parts, but also part machinery.

Attacks and Abilities

Phase One: Feugen and Stalagg

The encounter begins with two wight mini-bosses Feugen and Stalagg, each staged on their own platform and tethered to an adjacent tesla coil. Feugen and Stalagg each have 499,650 health. If they are not killed within 5 seconds of each other the slain wight will resurrect with full health.

Shared Abilities

  • Spell nature groundingtotem.png  Magnetic Pull — Pulls an enemy target from the opposite platform to the caster. This will always be the opposite wight's primary aggro target, and wipes that target's threat from the wight when cast.
  • Ability bullrush.png  Warstomp — Knocks back all enemies within 15 yards, dealing ~1500 physical damage.
  • Tesla Coil — Tesla Coils are linked to their respective wight. Should the wight move out of range, the link will be broken and the tesla coil will start damaging the raid.
    • Trade engineering.png  Shock — Instantly deals 4375 to 5625 Nature damage. Cast every second. Hits ~5 targets per cast. Unlimited range.


  • Spell shadow spectralsight.png  Static Field — Burns 500 mana from all enemies within 30 yards every 6 seconds, dealing shadow damage equal to the mana burned. Instant.


  • Spell shadow spectralsight.png  Power Surge — Increases the caster's attack speed by 200% for 10 sec.

Phase Two: Thaddius

When both adds are down, players have 15 seconds to jump to the central platform before the tesla coils overload and activate Thaddius. Thaddius has ~6.657 million health.

  • Spell nature chainlightning.png  Chain Lightning — Strikes an enemy with a lightning bolt for 2000 nature damage that arcs to another nearby enemy. The spell affects up to 15 targets, inflicting greater Nature damage to each successive target. Cast every 5-10 seconds.
  • Spell nature lightning.png  Polarity Shift — Polarize all nearby enemies, placing either a Negative Charge or a Positive Charge on each target for 60 sec. 3 sec cast. Cast every 30 sec.
    • Spell chargenegative.png  Negative Charge — Damage done increased by 10% per each nearby negatively charged ally. Deals 2000 nature damage to nearby allies that are not negatively charged every 5 sec.
    • Spell chargepositive.png  Positive Charge — Damage done increased by 10% per each nearby positively charged ally. Deals 2000 nature damage to nearby allies that are not positively charged every 5 sec.
  • Spell lightning lightningbolt01.png  Ball Lightning — Cast when no targets are within melee range. Inflicts 7000 to 9000 nature damage to an enemy target. 1 sec cast. Unlimited range.
  • Spell shadow unholyfrenzy.png  Berserk — After 5 minutes of being active, Thaddius goes into a berserker rage, increasing its movement speed by 150% and the physical damage it deals by 500% for 10 min.



Before the encounter, assign locations for positive and negatively charged people to stand. The most common assignment has negatively charged players to the left of Thaddius and positively charged players to the right.

Phase 1

Simply tank each sub-boss near where they start and DPS them down. Due to their mechanics, casters should fight Stalagg, while melee should fight Feugen. Mages and hunters can outrange Feugen's mana drain, so if the groups are too uneven then they can fill in for the missing spots. Note that these sub-bosses must be killed within five seconds of each other, or they will resurrect at full health(much like High Priest Thekal in Zul'Gurub).

Phase 2

All players head to Thaddius' platform. There is roughly 20 seconds between killing both sub-bosses and getting charged. Thaddius will cast Polarity Shift roughly every 30 seconds. Players whose polarity changes have 5 seconds to run to the location for their new polarity. There is no need to avoid other players changing sides, and they should run straight to his new position, using the shortest path available (that is, running through Thaddius). It is important for the raid to stand in two groups because Thaddius must be killed within 5 minutes (to avoid the berserk) and the damage bonus from stacking players on each side is needed to kill him that quickly. Hunters especially need to make sure they remain within range to maximize the charge debuff stacks.

Three important notes with this phase:

  • After the initial Polarity Shift, further casts will only shift half the raid's charge, while the other half retains the same charge. This is random. It is crucial that all 40 players individually pay attention to their debuff, as they may be required to move to the other side.
  • Players who miss the jump heading for Thaddius will not receive either charge, and will damage any nearby player upon successfully landing on the central platform. These players should stand on the central platform at a distance from the raid and wait until the next Polarity Shift, when they will receive a charge.
  • Players lose their charge when they die, and will have neither charge should they be revived in combat. Accepting the rez will cause them to instantly be killed (in addition to them damaging nearby players). It is therefore never advisable to use a battle rez or soulstone during phase two.

Thaddius doesn't deal very much melee damage to an appropriately geared main tank, so only 3-4 tank healers are necessary. The other healers should focus on the rest of the raid, as Thaddius deals heavy nature damage to 15 players every 5-8 seconds.


Thaddius hits for about 2k normal, 3.3k crushing. The damage multiplier the rest of the raid has can make holding threat for a warrior tank a little bit iffy. (Bear tank threat generation benefits from the damage multiplier, unlike warrior abilities, and is advantageous for this fight.)

In order to have a prayer of holding threat, the MT has to move with others of his charge, if he's unstacked by the debuff, he will find himself making frequent use of his Taunt button (Thaddius is tauntable).


A wireframe and textured model of Thaddius

Blizzard's release of the Anatomy of a Monster: Thaddius revealed some clues into the strategy of fighting this abomination.

At the start of the encounter, the players don't fight Thaddius himself; they battle two wights that are in the same room on two separate platforms. These platforms are not directly connected, so to fight them the raid has to split up and attack both wights at the same time. But it gets worse... the wights have the ability to snatch a player from one platform and pull him to the other, which is a way to split up the raid and divide their forces.

One central part of the whole Frankenstein myth is the way the monster was brought to life using lightning and electricity. Voltage is created when electric charges are separated; when the charges are brought together, the stored energy is released in an electrostatic discharge - a basic electric shock. When players finally go up against Thaddius, he will "polarize" the raid group by making half the raid positive and the other half negative. When positive and negative raid members get too close to each other... Well, let's just say that you want to get as far away from players with an opposite charge as possible, which further plays into the idea of separating the raid.


While Thaddius remains undefeated, the following screams are occasionally heard echoing throughout Naxxramas. The screams sound like those of a woman or child:

  • Pleeease!
  • Stop, please stop...
  • Help me! Save me!
  • Please, nooo!

These screams will cease after Thaddius is defeated.

You are too late...I...must...OBEY!
  • Eat...your...bones...
  • Kill!
Polarity Shift
Now you feel pain...
Killing a player
You...die now!!
Thank... you...
Killed first
Kel'Thuzad yells: Who dares violate the sanctity of my domain? Be warned, all who trespass here are doomed.
Killed second
Kel'Thuzad yells: Fools, you think yourselves triumphant? You have only taken one step closer to the abyss!
Killed third
Kel'Thuzad yells: I grow tired of these games. Proceed, and I will banish your souls to oblivion!
Killed last
Kel'Thuzad yells: You have no idea what horrors lie ahead. You have seen nothing! The frozen heart of Naxxramas awaits you!


Tier 3 Set Tokens
Item Class
 [Desecrated Circlet] Priest, Mage, Warlock
 [Desecrated Headpiece] Warrior, Rogue
 [Desecrated Helmet] Paladin, Hunter, Shaman, Druid
Non-set Loot
Item Type
 [Plated Abomination Ribcage] DPS Plate chest
 [Eye of Diminution] Caster trinket
 [Leggings of Polarity] Cloth legs
 [Spire of Twilight] +Healing staff
 [The Castigator] One-hand mace
 [Splinter of Atiesh] Quest Item

Defeating Thaddius rewards 100 reputation with the Argent Dawn.

Patch changes

External links