Thaddius Strategy Guide – Naxxramas (10)

wotlk classic naxxramas thaddius featured image

Thaddius is the final boss of the Construct Quarter in Naxxramas. A massive looming presence across the room, flanked on either side by his minions, Feugen and Stalagg, surrounded by electrical coils and arcing bolts. If you listen closely you can hear the screams of souls contained within him, silencing their pain by slaying him.

“Thaddius, built from the flesh of women and children, it is said that their souls are fused together – eternally bound within that foul prison of flesh.Commander Eligor Dawnbringer

This guide will offer a detailed, step-by-step tutorial on how to coordinate and slay the remaining three constructs in your way.

Role Summaries

Phase 1

  • Make sure you are coordinated with your team and are on the correct side
  • Keep your eyes on both Feugen and Stalagg so that neither dies early — they must die at roughly the same time!

Phase 2

  • Be very aware of your Polarity, moving as fast as possible
  • Never walk on top of the tank to avoid mixing Polarities

Phase 2

  • Make sure your DPS cooldowns are ready and active for this Phase, to make sure you can combine them with the Polarity damage buff

Phase 2

  • Make sure your DPS cooldowns are ready and active for this Phase, to make sure you can combine them with the Polarity damage buff

Phase 1

  • Be ready for Magnetic Pull, any tank healer will need to swap target very quickly
  • If you are on Stalagg’s side be ready for the big boost in damage caused by Power Surge
  • If you are on Feugen’s side, prioritize instant spells to compensate for the constant pushback of Static Field

Phase 2

  • DPS whenever you have the opportunity, the enrage timer can be very tight

Phase 1

  • Make sure to pre-pop a potion, the initial pull can be rocky while everyone gets into position
  • Be ready whenever Magnetic Pull happens and your target is swapped

Phase 2

  • Stay at the absolute maximum melee range at all times, giving as much space to the two Polarity groups as possible


Phase 1

Phase 1 will have you fighting Feugen and Stalagg separately, each having their own abilities as well as swapping the tanks periodically. The two must also be killed within 5-seconds of each other, otherwise, they will resurrect with full health, making this fight a lot more difficult.

Feugen deals constant Nature damage to everyone within 60-yards of him, causing pushback on casters and quickly burning down smaller health pools.

Stalagg will periodically increase his melee haste by 200% for 10-seconds, giving him a short period of heavy damage on the tank.


Every 3-seconds all targets within 60-yards take 2500 Nature damage. This will only reach players on Feugen‘s platform and is managed with consistent AoE healing.

Every 30-seconds, the tanks for Feugen and Stalagg swap places and threat with each other.


Every so often Stalagg will cast this, increasing his attack speed by 200% for 10-seconds. Handle this with defensive cooldowns, healthstones, healing potions, and whatever else you need to survive it.

Every 30-seconds, the tanks for Feugen and Stalagg swap places and threat with each other.

Phase 2

Phase 2 is the fight against Thaddius himself. Every 15-seconds he will cast Chain Lightning, dealing AoE damage to 5 targets, requiring healers to stay on top of healing.

At 30-second intervals, everyone alive will be given a Polarity debuff, either Positive Charge or Negative Charge. Players will need to only stack with players with the same Polarity as themselves, creating one stack of Positive players and one stack of Negative players, dealing massive damage to everyone if the Polarities end up being mixed. Players will also gain a stacking damage boost for every matching Polarity on them.

After another 30-seconds, Polarities will switch, randomly assigning Positive Charge or Negative Charge to everyone. You can absolutely get the same buff twice and need to be very cautious that you reposition yourself if your Polarity changes.


Every 15-seconds or so, Thaddius will cast Chain Lightning, hitting 3 targets for 3600 to 4400 Nature damage. This is a layer of AoE damage that needs to be handled by healers effectively so that they don’t end up falling behind and having people die.

Everyone in the raid will be charged with either a Positive Charge or a Negative Charge debuff. For each person on you with the same charge, you will get 10% damage. For each person on you with the opposite charge, you will deal 3500 damage to everyone around you. It is incredibly important that you stack on people with the same charge as you, and stacking incorrectly can very quickly wipe the raid. Without stacking you will also not have the damage to beat Thaddius within the 5-minute Enrage timer.

If no one is in melee range of Thaddius , he will throw Ball Lightning at his current target, dealing 17500 to 22500 damage. This should never happen, as your tank should always be in melee range of Thaddius.

Raid Composition & Preparation

This fight has no specific class or spec requirements, and as long as your group can deal enough DPS and keep coordinated you will be able to beat it.

You will want 2-3 Healers for this fight, one for each mini-boss. Phase 2 does not require much healing, and any healers that don’t need to heal can deal significant damage with the stacking Polarity buffs.

There are no strict requirements for DPS classes or specs here, you simply want a combination of good raid buffs and debuffs, as well as the best players you can muster.

You will need 2 tanks for this fight: 1 tank to start on Feugen and 1 tank to start on Stalagg. Thaddius himself only requires 1 tank, typically whichever does the least damage.

The Pull

thaddius frontal

Before pulling, the raid should be split into two groups, one on either side of the walkway. Ideally, these groups should be split into roughly equal DPS, but a lot of raids opt to split into ranged DPS and melee DPS groups. Both groups will need a tank and enough healers to survive as well. It is also worth considering your buffs and debuffs, as they will likely not be shared between sides, so having a caster side and a physical side can be a good choice.

Because the path up to Stalagg and Feugen is a ramp, it is strongly recommended that the group moves together and positions on the platform up top, instead of fighting on an incline. Both sides should also be synchronized in pulling, otherwise one side’s boss may try to run across immediately.

The Fight

Phase 1

thaddius p1 positioning

During Phase 1 the fight is relatively simple. The tanks will be teleported to the opposite side every so often, having to quickly adjust and make sure the bosses remain in a good position. Everyone else just does their normal routine, damage & healing. The only noteworthy part here is that the bosses will need to die within 5-seconds of each other, so you will need to pay attention to the other side, and if one side is dying a lot faster, everyone will need to be ready to stop DPS at a moments notice.

The Jump

While not a Phase, the jump is an important part of this fight that can in fact wipe your raid. When Stalagg and Feugen die, the raid will have to jump from their platforms onto Thaddius’ platform. This is a very simple jump that is hard to miss, but that will never stop it from happening. If anyone misses this jump, they will most likely die in the pool below because they cannot be healed, or they will take a long time to get back to the raid, having to swim back to the entrance, run around and jump again.

If someone falls off, it is important that they do not come back to the group and end up in the wrong Polarity group, or even end up without a Polarity. Always remember, no Polarity is the wrong Polarity. Because of this, they will need to synchronize their return or resurrection with a Polarity Shift, otherwise, they can wipe the raid very easily.

Here are some of the main things that can typically go wrong in this phase:

  • That one player misses the jump – You know who I mean
  • That one player loops back and misses the jump again, you aren’t sure why you expected otherwise
  • Someone falls and dies, getting resurrected without a Polarity and wipes the raid
  • Maybe it’s time to talk to them about it. You can summon them later.

Phase 2

thaddius p2 positioning charges

This Phase is mostly very simple, but it requires everyone in the raid to do it correctly. One player can easily wipe the entire raid here. The raid should be divided into 3 groups, one for Positive Charge, one for Negative Charge, and the Tank by themselves. The tank will be in front of the boss, while each Polarity will be on either side of Thaddius. The side for Positive Charge and Negative Charge should be clearly decided ahead of time so that there is no confusion.

Thaddius is a massive boss and as a consequence of this, his hitbox is equally huge, meaning you can stand a lot further away than you may initially think. This means your raid can easily be split into 3 groups that will not touch each other, having every stack be at max melee range or slightly further for ranged DPS.

Whenever Polarity Shift happens, players will have to adjust which side they are on. If positioned correctly, they should be able to simply run straight ahead, through Thaddius, and to the other side with no issues.

Here are some of the main things that can typically go wrong in this phase:

  • Someone doesn’t react to Polarity Shift, or reacts incorrectly, very quickly wiping the raid
  • Someone is resurrected without a Polarity, wiping the raid
  • Players walk too close to the tank during Polarity Shift, killing them

If your raid can communicate, coordinate and work together, this fight is very simple, but it does require everyone to be on top of the mechanics, one player sleeping can easily spiral into a quick wipe.

Congratulations on defeating Stalagg, Feugen, and Thaddius! With the Construct Quarter behind you, you’re one step closer to Kel’Thuzad.


About the Author


I love MMOs of all shades, especially the nitty gritty numbers parts of them. You might recognize me from the Shadow Priest discord, otherwise I play a little bit of everything, especially games with support roles available.
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