Enemies: Dredge and some elementals.
Video guide [KING].
Current record (Bombs): 48.
Current record (Turret): 49.
You start in a huge area with 4 locked gates, 4 pressure plates, 3 cages and lots of dredge. The idea is to stand on pressure plates to open gates for other players. At the end there is a console which opens all gates permanently.
Go up on the ramp on your left to get on the first locked gate. Killing aggroed enemies is highly recommended because then you can make up a plan and take a look around the area without any pressure. However enemies inside cages respawn so just randomly rushing somewhere is pointless and will just get you killed.
The first gate is opened by standing on a pressure plate which is located on the first cage. The first cage can be reached by simply going to the left path. Only one player should do this because the gate immediately closes when you step off the plate. If additional players help with the first gate then you will have problems with the next gates.
All cages have lots of enemies so prepare accordingly. Take mobility so you can get it and out fast and defensive skills so you can tank longer. Stealth is very helpful and can be acquired from consumables like Harpy Feathers (consumable), Ash Legion Spy Kit or Order of Whispers Spy Kit but is not required. As a gate opener your job is to stand on the pressure plate until rest of the party gets through the opened gate.
If you aren't the gate opener then be ready to move through the cage as fast as possible. If you are too slow you may get the gate opener killed or even get locked behind if he can't wait any longer. This often leads to a full wipe in the last room because of the extra pressure. If something goes wrong tell your party to wait unless you know they can handle it.
The second gate works exactly same as the first gate. The second cage has a pressute plate and it can be reached by taking the path on the right side. However when practising it's recommended to first kill the enemies at the second gate to reduce pressure. The second pressure plate also opens the first gate which allows your 5th player to move in. The gate opener should stand on the pressure plate until 3 players have entered the second gate and the 5th player has entered the first gate.
The last area is a cage with 2 pressure plates, 2 gates and a console. The console is locked behind a gate which opens when both plates are pressed. This also opens all previous gates which let's the 2 players get in. To open the final gate, one player has to hack the console for 10 seconds without enemies hitting him or a player stepping off his pressure plate.
The console is difficult to hack with only 3 players because a veteran dredge appears right next to the console after about 2.5 seconds of hacking. The dredge will aggro on the hacker unless he is stealthed or another player attacks him quickly. Also the players standing on plates will take lots of damage because they can't dodge and may even get knocked out of their pressure plates.
The easiest way is to use stealth. A thief can stay permanently stealthed while hacking and also give some stealth to other players. This should be done right before the second gate opens because stacking stealth is much harder when enemies are near.
If this is not possible then you should stop right after entering the second gate. You can just wait there until the 2 remaining players get to the second gate and then stand on the plates to let them in. Those 2 extra players make it much easier because they can kite the enemies. If you are kiting then take control skills to reduce pressure. Also remember to keep an eye on enemies spawning near the hacker.
Keep in mind that a common tactic is just to rush in and hope that it works out. On lower scales this will probably work fine because enemies don't deal much damage so just either go to a pressure plate or the console depending on what others are doing. If it doesn't work out then suggest something more intelligent.
The last gate opens when the hack is done. Just rush in all way to the top and kill any following enemies.
Skipping initial enemies is risky because the extra pressure may lead to a wipe in the last cage. However it's much faster so it's recommended for experienced groups. Stealth and Portal Entre makes this much smoother.
You can try killing about half of the normal enemies in the last cage if you have problems and no one can use a thief. This will reduce the pressure a lot even though they will respawn shortly.
You should have a thief on the party to trivialize the last cage. It doesn't really matter which 2 players open the first two gates as long as the thief is in the main group. Stack swiftness right when you spawn since it lasts a while and helps the gate opener to move faster.
The main group stays at the spawn and starts stacking stealth and swiftness when the gate opener is about half way. Stealth ensures that no enemies follow you through the first gate which lets you stealth again easily. Again stack stealth and swiftness when the second gate opener is about half way.
You can stack even more stealth bit after the second gate but it's not necessary. Just make sure you don't hit any enemies so you won't get revelead. The thief gets to the console and uses Shadow Refuge to hack the console safely.
You will have enemies following unless everyone managed to stay stealthed the whole time. The options are either killing them or killing yourself. If you kill them then run up and pull them behind a corner to maximize area damage. If you kill yourself then everyone expect the thief should die as soon as possible. Doing this fast requires some practice so just killing the enemies is recommended.
It's possible to jump over the first gate as long as you are out of combat (Video). Swiftness helps but is not required. This requires some practice.
Blinks can be used to teleport to the second cage from the second gate. This saves some time, especially if you have a quick way to get back. Don't use this on random parties because it probably just confuses them.
The console hacker is actually launched if a player steps off his pressure plate. This can be countered with stability or invulnerability so you can just keep hacking. This is very useful if you expect your party to mess up or if you want to do it with only 2 players.
The last cage can be done by a mesmer and a thief. The thief opens the first gate and the mesmer uses Portal Entre before the first cage and after the first gate. This allows the thief to get in too. Wait for the portal cooldown and repeat the trick for the second gate. However this time the mesmer should first take the portal to the thief so they can stack stealth safely.
At the last cage you can go directly to the pressure plates or stack more stealth in the corner. The mesmer uses Mantra of Concentration, then Blink towards the console and quickly starts hacking before it closes. At the same time the thief uses Shadow Refuge to keep them both stealthed.
If you there is a trouble with boons consider using Larcenous Strike.
Use Shadow Refuge at the console to keep you stealthed most of the time.
Use Shadow Trap when doing the second pressure plate to get instantly back.
Use portals to get everyone quickly through on the first and the second gate. Use Mimic and Portal Entre before the first cage. Use Portal Exeunt bit after the gate to let the gate opener portal through. Repeat the same trick for the second gate.
Take Blink if you need more mobility when placing portals or opening gates.
Use Spectral Walk before going to a pressure plate to quickly get out.
The start of tunnel has aand some normal-Dredge. Don't aggro them until you have killed any following enemies. Mining Suit summons normal dredge so you may get overrun unless you can focus him down or keep him disabled.
The tunnel continues to either left or right direction which depends on the fractal scale. The left tunnel is for Guns path and the right tunnel is for Bomb path.
The initial enemies can be skipped but it's not recommended without stealth because they may follow you a long way. There are also more enemies further in the tunnels so you can easily get overrun.
The left tunnel has several normal dredge which you should kill to observe the area without any pressure. Try to pull them together or break line of sight to kill them faster.
On left side of the tunnel there is a Mining-Laser Rack. Interacting with it will give you a mining gun which replaces your weapon skills with a single skill. This skill must be used to destroy the door at end of the tunnel. Keep in mind that the door will only take damage when 3 players are using the skill on it.
There are 3 turrets between the rack and the door. These will shoot AoEs in a specific pattern which will destroy the gun if you get hit. Getting through is easy as long as you study the pattern carefully. Keep in mind that the AoE markers aren't harmful. Markers appears 0.9 seconds before the explosion and stay about 0.7 seconds after the explosion.
Hug either the left or the right wall because some explosions are only in one side. The front and back explosions trigger twice so don't rush in after just a single explosion. Any kind of teleportation will automatically drop the gun so only use teleportation skills to get back to the rack. The gun also removes all your endurance so you can't dodge through explosions. Other movement skills work though.
If you lose your gun then go just grab a new one. You can try as many times as needed so there is no pressure.
Once you get through wait until there are 2 additional players and then use the skill 1 on the door. This will overheat gun which makes it explode if you try to use it again so just drop it. Successfully attacking the door damages it for 25% of its maximum health and spawns several dredge behind you. Just kill them to make next runs easier and then go grab a new gun.
You have 2 extra players because only 3 are needed to destroy the door. Make a plan to use those extra players to maximize your efficiency. The simplest plan is to have 3 dedicated runners and 2 fighters. Fighters just focus on killing the dredge.
However if one player is able to move much faster than others then you should rotate the roles. Initially all players are runners. Decide which 2 players use their guns first with the fastest player who will always be a runner. The remaining players wait with their guns ready. After hitting the door the fastest player gets another gun and 2 other players become fighters. Once dredge are killed the fighters become runners.
Powersuit is harder thenbecause his attacks have a bigger range and require fast and accurate dodging. Powersuit has 5 attacks; Slash, Smash, Bomb, Shock Wave and Mending.
Slash is his basic melee attack which has a surpisingly high range and radius. He pulls his right arm back and does 2 quick hits for lots of damage and bleeding. You need to either dodge really fast or position yourself right behind his back.
Smash is used when he glows and gains stability. The attack causes 3 room-wide PBAoEs in 3 seconds which deal lots of damage and agony. You need use 2 dodges accurately to avoid all hits. Consider taking defensive skills like blocks and immunities.
Bomb is used when he raises both arms. He will shoot 2 waves of bombs at every target which will explode after few seconds. Try to move out of them but feel free to dodge if you get surrounded. Just don't waste your dodge before the second wave lands. Bombs are projectiles so they can be reflected or absorbed. However Powersuit is immune to their damage.
Shock Wave is used when he jumps. When he lands he will shoot short ground projectiles in all directions. One projectile won't deal much damage but you may get hit multiple times.
Mending is used when he kneels down. This is the powerful healing ability which also removes conditions. It will get interrupted by normal attacks as long as he has the superheated debuff.
Keep some distance so you won't get hit by Slash or Shock Wave. Take at least one defensive skill if you need to avoid both Bomb and Smash. Keep in mind that Smash has a huge range so you need to avoid it some way.
Melee is difficult because of his high damage basic melee attack. You have to either position yourself carefully so you don't have to dodge when he uses Slash on soneone else or take multiple defensive skills. If you get focused your dodges will be used against Slash so you need something against Smash.
Don't waste dodges against Shock Wave unless absolutely needed. You can move a bit away from him to reduce damage taken.