About thaddius . Feel free to correct if i am wrong thank you

Thaddius is the end boss of the Construct Wing of Naxxramas. He's a two phase fight, starting with fighting two constructs, Feugen and Stalagg. Once they die, the main fight of Thaddius begins.

Raid Setup (25 man)
The raid should consist of 2 tanks, 6-8 healers and the rest DPS.
Boss Abilities

Feugen
25 man: Melee hits for about 4.5k on plate. Feugen has 2,100,000 HP.

Static Field: This is a constant passive aura that Feugen has. It deals nature damage to every target within 60 yards of Feugen every 3 seconds. The ability hits for 3500 in the 25 man version, and 2500 in the 10 man version. It will hit everybody on Feugen's platform, but not the other half of the raid on Stalagg's platform.

Magnetic Pull: This pulls Stalagg's tank to Feugen's platform, and swaps the threat lists of the two mobs. It is used roughly every 15 seconds.
Stalagg
25 man: Melee hits for about 6k on plate. Stalagg has 2 100 000 HP.

Power Surge: Stalagg increases his melee haste by 200% for 10 seconds. This is not dispellable. Stalagg's tank healers do not have anything else to heal at this point of the fight so it should be no issue healing through this. He uses this ability roughly once every Magnetic Pull; however the use of this ability is very random.

Magnetic Pull: This pulls Feugen's tank to Stalagg's platform, and swaps the threat lists of the two mobs. It is used roughly every 15 seconds.

Important note about Stalagg and Feugen:
If Stalagg and Feugen are not killed within approximately 5 seconds of each other, they will resurrect each other with full health.
If either mob is pulled off their platform, the Tesla Coils linked to them will become unlinked, dealing massive nature damage to everyone in the room, generally causing a swift wipe.
Thaddius
After Stalagg and Feugen die, both mobs' Tesla Coils will link to Thaddius. After about 13 seconds, he becomes targettable, and after 15 seconds he becomes active, giving the tank a small window to prepare the pickup.

25 man: Melee hits the tank for 8-10k with a rather slow swing timer. He has 27 600 000 HP.

Ball Lightning: If Thaddius has no target in melee range, he will chain cast this ability on his primary aggro target for 17 500 to 22 500 damage. If the tank dies, this is the ability Thaddius uses to wipe up the raid in very short order.

Berserker Enrage: 6 minutes after he becomes active, Thaddius will enrage, increasing his damage done by 1000%. He will one-shot-kill Shield Walled tanks, and his Chain Lightning will kill those it hits. It takes an average raid about 10-15 seconds to wipe after this, depending on how many hits the tank can avoid.

Polarity Shift: Thaddius changes the polarity of the entire raid, giving half a positive charge, the other half a negative charge. Which polarity every player gets assigned is completely random: every time this ability is cast, every player of the raid will be assigned a random charge independent of their former charge.

Players with opposite charges standing within 10 yards of each other will deal 3500 nature damage per tick to each other in that 25 man version, and 2500 nature damage per tick in the 10 man version. Players with the same charge standing within 10 yards of each other will gain a buff giving 10% increased damage done per stack. 10 people of the same polarity will for example have 9 stacks of this buff, increasing all their damage done by 90%. This buff is needed to kill Thaddius before the enrage.


Strategy

Phase 1
The raid needs to be split in two, with one tank and roughly half the DPS capacity in each half. One tank healer and most of the raid healers should be put on Feugen's side, whilst the remaining tank healers are put on Stalagg's side. Position the two groups at the start of the ramp on their respective platforms.

The Pull
The fight starts with the two tanks running up the platform and engaging the mobs. The raid should follow and start DPSing swiftly. The mobs will not be pulled before you're a good way up the ramp; it's almost impossible to accidentally pull the mobs off their platforms during the pull. Have the tanks time it; use voice comms to count down the pull just in case.

The Fight
During phase 1, the two mobs will swap tanks and threat with the other mob roughly every 15 seconds. What this means is that the two tanks switch places: Stalagg's tank goes to Feugen and vice versa. Each tank inherits the former tank's threat on the mob, meaning there is no need for the DPS to hold fire when this happens. Healers assigned to the tanks should be aware of this however: they of course need to switch to the newly arrived tank when this ability is used. Both mobs are Taunt-able.

Tanks: Be prepared for the tank switch. It may disorient you for a few seconds. Make loads of threat.

DPS: Watch the other mob's health! It's helpful to hold fire at around 15%, and then time the kills. Remember, you will want them to die within 5 seconds of each other or they will both resurrect.

Healers: Keep the tanks alive. During Stalagg's Power Surge, bigger heals will be needed, and Feugen's Static Field will damage the raid, and has to be healed up. Be aware of tank changes when the Magnetic Pull is used by the mobs.


Phase 2
Once Feugen and Stalagg die, the entire raid should move on to the main platform at which Thaddius is standing, waiting. Note there is a gap between the platforms; you have to jump. Priests and mages can Levitate and Slow Fall respectively; rogues and druids can Sprint and Dash to jump further. Aspect of the Pack / Unholy Aura on the raid is helpful to make sure no one falls off. If you don't make the jump, you will fall into the acid, taking minor damage. If this happens, simply run around as fast as you can and try again (the pink arrow in the phase 1 pull picture shows the pathway through the acid and back up). The picture below should give you a rough idea of the jump distance.

After approximately 15 seconds, Thaddius will become active. He can be targeted a few seconds before he starts hitting, so the main tank has time to get aggro. Very soon after he becomes active, the first Polarity Shift will be cast on the raid (it has a cast time). This is the defining moment of the fight. Watch your debuff bar carefully: negatively charged raid members should run left (red dot), and positively charged members should run right (blue dot). If you fail to move in time, you will deal damage and receive damage depending on how many other players you are close to. Note that the main tank should move as well.

All raid members with similar charges should pile on top of each other, to give the stacking damage buff. Since half the raid will be of the same charge at any one time, everyone should have least 11 charges in the 25 man version, and 4 charges in the 10 man version. If this is not the case, someone is either dead, or too far away from the group. You get approximately 3 seconds from the Static Charge debuff becoming active until it starts dealing damage to nearby oppositely charged players, giving you a few seconds of reaction time.

Are you looking at me?Throughout the fight, Thaddius will re-cast Polarity Shift every 30 seconds. Every time this happens, everybody has to watch their debuffs. If it changes, run straight through the boss to the other side. If it stays the same, stay put and keep DPSing or healing. The tank will have to move each time his/her debuff changes, just like the rest of the raid. If you have to move, do not finish casts. Run immediately.

Thaddius will also cast Chain Lightning. This is fairly trivial to heal through.

The fight continues like this until Thaddius dies.

Miscellaneous Tips
The raid will need all the DPS it can get for early attempts on this boss. If people die, spend combat resurrections: a dead person is not only lost personal DPS, but also lost DPS for every buff stack he is not keeping up (this is 10% less damage for every other raid member on average). Note that when a raid member is combat resurrected, this must be done away from the rest of the raid (for example on the green dot). If this is not the case, the combat resurrected person will risk immediately dying from Polarity Shifts.

From pull to enrage there is 6 minutes. If you use a Heroism / Bloodlust immediately after the first Polarity Shift, the Exhaustion debuff you gain after the effect wears off will expire in time for another Heroism / bloodlust before the enrage time hits. This is why you will want to bring 2 shamans as the minimum.

Pet classes are weak in this fight: hunter pets and warlock minions do not benefit from the Polarity Shift damage buff. Shaman spirit wolves do not benefit either, but this is less of a hit on their DPS.