Minimum 550 AP on 6-man, 600 on 4-man.
A really big brain.
Note: There are ZERO Dragonbloods in this dungeon, and every dungeon after. You die, you're done unless you have revive charms or there's a Summoner who can send their cat over to revive.
At the bottom of the pit there is a Destroyer miniboss, with a lot of trash mobs. Tag him, then run around the right side of where you dropped down. This will trigger all the trash to come after you, so lead all of them to the corner to burst them down. If there is an Assassin, they might be able to solo stealth kill him, but this might take a while as the miniboss has 1.9 million health and there is a risk of them messing up, so it might be faster to get the entire party to sic him.
Take the dragon pulse that spawns and clear the trash leading to the boss.
Boss 1: Force Master Jang Ghibu (Main boss) + 2x Destroyers Mengwol and Muwol (Waifu adds)
Force Master has a 45% x 2 damage reduction shield. Get someone to tank both Destroyer wives on the corner and hurt both down to 70% so the boss gives them his shield.
DO NOT kill either of the Destroyer Wives or the boss enrages immediately.
Mengwol (Destroyer wife standing to the left of the boss has a lot of red attacks). If there is a ranged, let them tank her.
Muwol (Destroyer wife on the right has yellow attacks that are blockable). Let a BM/KFM tank her.
If there is a Summoner, let them throw their cat on both wives.
Force Master will periodically say something and then target the furthest person; he will freeze them and deal high damage to that person; CC him.
Once Force Master is at 70% and 40%, he will call back the wives. They will jump to the center; iframe when they land or you will get frozen. There are ice flower patches on the ramps; don't step on them or get frozen. Force Master then does a three-hit field-wide area of effect twice, and it hurts a lot, especially if you get frozen. Before the second AoE the wives will be doing fire spin knockups around the room. The wives then heal back to full health and Force Master gets back his shield.
At 20%, Force Master will do his 3 hit AoE once, and the wives instead just spin where they are. He will periodically cast this ever few seconds. Burst him down quickly.
Be very careful bursting him down from 40% to 20%, as the wives will give back the shield at 40% but won't take it back during 20% as the 3 hit AoE heals them.
Once Force Master is dead, the wives will get dazed for a good amount of time before going back to fight. Kill them.
Lots of trash mobs in the way. If there is an Assassin, let them use Lotus of Rescue to teleport the party past the trash.
There is a Force Master miniboss. Fight him in the corner, as he spawns pinballing robots. Alternatively kill the final set of trash mobs and fight him at the edge, as the pinballing mobs don't go over there; careful not to reset him.
Play Mario up the steps. Activate a switch to spawn a Dragon Pulse to skip the steps.
Boss 2: Iron Juggernaut (Ironsides/Ironheart 3.0, "Iruga 2.0")
Standard Ironsides/Ironheart Rotation, of frontal swipes and laser, along with an area of effect that is CC-able.
If you are tanking, be very careful when fighting afar. His maximum range threshold is 4 meters and if you are out of it he will force grip you back in. If you do not resist, he will do a field-wide area of effect slam and it hurts a lot.
Periodically he will summon three blue robots that try to heal him. If you are not the aggro holder, get off the boss and kill them immediately.
Once the blue robots are dead, three red robots will spawn. Do not attack yet as they will jump to Iron's aggro holder. Kill them quickly so they drop a shield, or they self-destruct and drop nothing. CC them if they try to explode. At least two shields are needed for the next mechanic.
More blue robots spawn and try to heal the boss. If you are not holding a shield, kill them.
Iron becomes untargetable and fires several missile volleys at the furthest person. That person needs to run up one of the ramps to the sides and slowly make their way down.
One shield user (one of them must be the tank) run up the other ramp and try to become the next furthest person. Iron then fires three small lightning pellets, block them with 1 on the shield (0.8 second block window) while going down the ramp, and then throw the shield at Iron.
The second shield user goes up the ramp and becomes targeted for two frontal lasers. If positioned correctly, the lasers won't hit.
Iron fires three more lightning pellets, block them and then throw the shield. If there are 5 or more pellets, Iron gets knocked out of his invincible state and can't be grabbed except for grapple.
If the mechanic is done wrong, Iron does three field-wide AoEs in succession. If you are not a Force Master, or a Blade Master with Hongmoon Winged Protector, you are basically dead since you still can't target Iron.
Lots of trash mobs, several of patrolling sirens that spawn turrents and have force grip. Try to glide over the sirens as they run backward. If there is an Assassin, let them use Lotus of Rescue to teleport the party past the trash, but they need to be careful as the sirens have true sight.
Take the Dragon Pulse to the final chamber.
More patrolling sirens with blue lasers that stun you and red lasers that instant kill you. Jump over them and activate a switch that removes the lasers.
Boss 3: Lord of the Flame (Infernal Lord 5.0)
Note: You need at least four people alive to do mechanics. If there are less than four, it's basically a wipe. Everyone needs to coordinate.
Assign one person to be the "Marker."
Assign one person to be the "2". This is usually the aggro holder.
Assign two people to be the "3".
Optional 6-man: Assign two people to facetank lightning spheres.
Standard Lord rotation of swipes and flame breath.
Lord jumps to the furthest person. The first three people who hurt him will then get marked with Time Bombs that cover 8 meters; move away and iframe the explosion. After getting bombed, Lord spits giant puddles at the bombed people; only rush in when in the spitting animation. He then does a field-wide roar.
Boss jumps to the middle and marks the furthest person from him.
Boss spawns two lightning spheres. Facetanking these gives a buff stack that gives a damage bonus.
The lightning sphere tankers must absorb both for one each. If no tankers were assigned, both the Marker and 2 must absorb one.
Boss throws a chain of lightning at the marker. Exactly two people, including the marker, must facetank this, no more and no fewer or anyone facetanking without sufficient people will cause the marker to die instantly.
The Marker must stand in front of the boss; 2 must stand just behind him/her.
Death by lightning skips past near dead phase.
If you take too many lightning buffs, you die instantly. Lightning spheres gives 0.5 of a buff and lightning chain gives 1.0; 2.0 = instant death.
Boss tries to grab closest person. He will absorb their lightning buff and then throw them; the marker must be the one to get grabbed, otherwise anyone else must be the marker instead.
Boss jumps at the aggro holder.
Boss marks the furthest person again.
Boss spawns two lightning spheres again.
The lightning sphere tankers must absorb both for one each again. If no tankers were assigned, both 3s must absorb one each.
Boss performs a lightning chain on the marker. This time three people are needed to facetank.
Again position marker in front of the boss, and the 3s standing behind him/her.
Boss grabs again. Boss hurts himself by 8% of his health for every 2 lightning transfers, or 32% for 8 transfers in total. But if he absorbs 9 he will immediately enrage.
Boss performs a 4 hit ground pound. This is CC'able.
In 4-man, you are required to stall the boss for 6< seconds so lightning buffs time out to make up for the loss of 2 extra people. Make sure you pause a few seconds after CCing before following-up.
If there is a Destroyer or Blade Dancer in the party, let them grab.
If there is a Summoner, iframe the first pound and then CC into cat grab.
If there is a Kung Fu Master, let them air combo into grapple. Don't interrupt their air combo if melee.
If there is a Blade Master, let them air combo. Don't interrupt if melee.
If there is an Assassin, let them air combo into Webbing. Do not attack the web or it will be interrupted.
If you don't have any of these, you're forced to iframe three of the pounds, then CC into aerial.
Boss marks the furthest person.
Boss doesn't summon spheres and goes straight to lightning chain. Two people are needed to facetank.
Once again, the Maker and 2 must facetank this, as the first time.
Boss grabs again.
Boss does an field aoe roar; iframe this.
Repeat 1 and 2.
Similar pattern to 90%, except the marking is the closest person and the number of people for lightning is 3-2-3.
Avoid the 6th grab so he doesn't dip into 30% and start the next mechanic with everyone still having lightning buffs.
Repeat 1 and 2.
Same as 90%.
If the 6th grab was not avoided, avoid the 9th. He will immediately enrage and wipe on 9 lightning transfers.
Repeat 1 and 2.
He will now do his field-wide area of effect roar after a fire breath; be very careful.