Underground Facility Fractal

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Underground Facility Fractal

Underground Facility Fractal map.jpg
Map of Underground Facility Fractal

Fractals of the Mists

Underground Facility Fractal.jpg
Underground Facility Fractal

Delve deep into an underground dredge facility.

— In-game description

The Underground Facility Fractal is one of the Fractals of the Mists that occurs at levels 8, 17, 29, 43, 53, and 81.


  • Event boss (tango icon).png
    Find a way to higher ground.
    • Fractal Difficulty Scale: x
    • Personal Fractal Level: x
  • Event boss (tango icon).png
    Push deeper into the dredge stronghold.
    • Fractal Difficulty Scale: x
    • Personal Fractal Level: x
      (if bombs)
    • Use bombs to destroy the door.
      (if guns)
    • Assemble a firing team, arm yourself with dredge mining lasers, and destroy the reinforced door.
    • Reinforced Door
      Event bar.jpg
      Event swords (tango icon).png
    • Firing-team members present at door: X/3 (if guns)
    • Subdue dredge forces.
    • Dredge
      Event bar.jpg
    • Rabsovich
      Event bar.jpg
      Event boss (tango icon).png

      (if ice elemental)
    • Vanquish the rampaging ice elemental.
    • Rampaging Ice Elemental
      Event bar.jpg
      Event boss (tango icon).png

      (if power suit)
    • Destroy the dredge powersuit.
    • Dredge Powersuit
      Event bar.jpg
      Event boss (tango icon).png


First Room[edit]

There is a plate at the end of the left side path leading up from the first raised platform as you walk in. Have one person run up and stand on it to open the first gate. The player doing this only needs to stand on the switch long enough for at least one person to pass the gate, after which s/he can run back to rejoin the others.

Next, one person stands on the plate on the upper right path that is just past the first gate. Again, the player only needs to stand on the switch long enough to let at least two other players through the second gate.

Once inside the central room, dredge will continuously spawn, so it's important to perform the rest of the procedure quickly. There are two plates in this room, one left and one right. Once both plates are activated, the door to the control panel will open. At this point, the person on the right side plate from earlier may come down and enter the middle room as well. While the control panel is accessible, it must be activated and allowed to run for about 20 seconds without interruption for the door to open to the next area. Dredge will spawn and try to attack the person using the control panel and the people on the plates. If either of the plates aren't being stood on, the control panel door will shut, interrupting the procedure. A common strategy for this is to allow the 4 party members who are not standing on the second button to get inside the room and, once inside, clear dredge around the room while ignoring the veterans. Then, have the two tankiest players stand on the buttons on either side of the room, at this point the 5th party member can run into the chamber and begin channeling the control panel while the remaining two party members kite dredge away from the control panel and side buttons.


The buttons do not remain depressed if the people on them are fully dead. The buttons will remain depressed, however, if the players on them are only downed.

Second Room (to the right)[edit]

Clear the dredge leading up to this area by grouping them up using line of sight behind the pipe on the left wall. As you enter this area there will be a security dredge suit with a permanent aura denoted by a red circle around it. On the right side of the platform that this dredge suit is patrolling will be a partially caged section with a pipe that periodically dispenses 3 bombs. When these bombs are dispensed, dredge will appear to steal the bombs, they do not need to be fought, players merely need to quickly pick up the bombs to avoid the dredge stealing them. Once a player picks up a bomb, they will leave the caged area and to the right, against the back wall of the platform is a cloud of smoke constantly being released from one of the pipes. Players need to run through this smoke cloud to gain a long stealth. Players who move into the dredge suit's red aura will be revealed.

Once stealthed, players move up the hallway in front of them. Stationary turrets are located on either side of the hallway which create permanent security zones. These zones are demarcated by two straight horizontal red lines on the ground. Players who are unstealthed and run through these security zones will take damage, be stunned, and lose their bombs. Once a player makes it up to the end up of the hallway, there will be a pipe on the left wall to interact with and dispense bombs. 9 bombs in total are needed and the total number of bombs successfully deposited by your party will be shown in the top right of the screen. There is a second stealth cloud located opposite the bomb depository pipe that players will use to stealth back to the bottom of the hallway to retrieve more bombs and repeat this process. When a bomb is deposited, several dredge will spawn near the bomb depository, they don't have to be dealt with, however, as long as players remain in stealth. As more bombs are placed in the depository pipe, more dredge security suits will spawn throughout the hallway, including one that will patrol on to the second stealth cloud at the top of the hallway. Players need to be careful of this dredge suit in particular because being revealed will cause the dredge at that end of the hallway to begin attacking any unstealthed players. The bombs have a 20s timer that begins upon pickup. It is displayed on the character's boon bar by the Bomb.png Bomb Timer effect. The stealth lasts quite awhile, but the player should be aware of how much time remains, as the bomb exploding will Reveal them.

Once 9 bombs are placed in the depository pipe, players will be able to interact with a detonator across from the pipe which will destroy the gate blocking the end of the hallway. It is advised for parties to group up at the detonator before destroying the gate since the dredge that have appeared during bomb placements do not despawn at this point. Progress through the destroyed gate to move to the next part of this fractal.

Alternate Second Room (to the left)[edit]

Once players kill the dredge leading into this area they will quickly note the orange AOE circles that appear in waves along the large ramp leading up to the right. These AOE circles must be avoided as they cannot be disabled. As players enter this area, on the left wall, will be a small box that players need to interact with to retrieve special Dredge Mining-Laser rifles. Upon picking up this bundle, players will lose all of their endurance and so be unable to dodge.

Players carrying rifles need to advance up this large ramp being bombarded with orange AOE circles. If hit while carrying a rifle, the rifle's 1 skill changes icon and becomes unusable. If this happens, the player needs to move back down and retrieve a new rifle. The easiest way to move up the large ramp is to hug the left wall, when the ramp levels out, there will be a pocket of safe area along the left wall. Players need only to wait for the waves of AOE to move past them and then move out of this safe spot, continuing to the left and toward a large targetable gate. 3 players need to be present in front of the gate with active rifles at the same time. The number of players within range of the gate will appear in the top right of the screen.

Players will activate the 1 skill on the rifle to begin destroying the gate. All three players at the gate need to use their 1 skills at the same time, and so it is advised that a party counts down before attacking the gate. When the gate reaches 75%/50%/25%/0% accordingly, the rifles' 1 skills will become unusable as if they were hit by the orange AOE circles. At this point, dredge will spawn near the gate that the party will need to quickly kill. Then repeat this process, returning back down to the box to retrieve new rifles. After the gate is destroyed, the party progresses through to the next room and the next phase of this fractal.

Third Room[edit]

A champion dredge, Rabsovich, and a veteran dredge await you in this room for a mini-boss fight. This fight is fairly easy and straightforward. Simply pull Rabsovich to the rear of the dredge carrier using line of sight and have your party fight him there. He will be accompanied by a veteran dredge along with any dredge who your party pulled into this room from the previous phase, these can all easily be AOE'ed down with Rabsovich. Rabsovich will periodically create an orange AOE rectangle leading out from his body in front of him. After a short delay, players in this AOE will take damage. He will also raise his shield throughout the fight and begin blocking all attacks while also dazing anyone who attacks him. During this time is a good chance for your party to take care of any mobs still alive around Rabsovich. When Rabsovich dies the fight will end and the dredge carrier will activate and drive through and break down one of the walls. Continue through this broken wall to reach the next and final area.

Legendary Dredge Powersuit[edit]

This boss has four basic attacks: an AOE stomp that does moderate damage, a standard physical attack that does high damage, a large AOE attack where he pounds the ground sending up large dust clouds and doing moderate agony damage, this ability is easily double dodged, and an AOE cluster bomb attack that does massive damage and can overlap resulting in one-hit kills for even the most heavily armored characters. The bombs can be evaded while exploding by dodge rolling, it is risky but possible, it's better just to move out of the blast radius. It also has a healing ability similar to a golem, where it plants itself in the ground, and the group must Interrupt the heal. If the boss is affected by the Superheated debuff from the buckets, this heal is interrupted by any damage done to the boss. If the boss is unaffected by the Superhated debuff then actual control effects need to be used. Condition damage is found to not affect him in the way it does normal mobs. At this point it is unknown whether this is intentional or a bug.

The room is surrounded by a platform all the way around with buckets of molten ore and control panels for each on the platforms. At the beginning of the fight, the boss is nearly invulnerable. The strategy is to have one player, preferably a character that has the weakest ranged damage of the group, to climb up to the platforms surrounding the room to operate the controls for the molten ore buckets. The strategy is simple: kite the boss underneath a bucket and dump the molten ore on it, giving it a debuff of Superheated denoted by a blue shield. The debuff allows the boss to be damaged much more effectively and lasts 30 seconds. Because the cooldown on the ore buckets is closer to 45 seconds, it is advantageous to kite the boss from bucket to bucket. Be sure to have all members kiting the mob stacked together and pulling in the same direction so if the Powersuit breaks aggro on one character, he is being pulled in the same direction. This can create problems with evasion but is essential to quickly downing the boss. It's best to envision your character pulling him with a fishing pole. As soon as the bucket has been dropped, circle around and pull him the opposite direction. It is important to assign a secondary bucket activator in the case that the primary person goes down. This is important because it keeps the debuff going as well as allows a quick response revive for the person going down.

The target area for the molten ore is marked by a lack of snow on the ground. When choosing a kiting path, the team can either go back and forth between two buckets, or kite around the room in a circular pattern. The back-and-forth path is easier on the person running the controls, as the distance is shorter, however the circular pattern is safer if a member of the team goes down, as they have longer to be revived. If there is a mesmer in the party, the Feedback ability is of particular use in this fight. If timed properly, it will reflect the cluster bombs back onto the mining suit, not only protecting the party from this most deadly of attacks, but resulting in massive damage to itself, speeding up the fight immensely.

Alternate Boss Legendary Rampaging Ice Elemental[edit]

Similar to the Powersuit fight, lure the boss under the molten buckets to make the boss vulnerable to attacks. The boss also summons smaller Veteran Ice Elementals that respawn when killed.

The Elemental will occasionally visibly kneel and start healing the damage he has taken. The group should Interrupt the heal by using a stun or knockdown skill on him, even if he is otherwise immune to the interrupting effect. This should be a priority for the group, since any healed damage will need to be re-inflicted, prolonging the fight. A necromancer's flesh golem's charge ability can also interrupt this.


Underground Facility Fractal Stabilizer Fractals of the Mists (achievements).png Fractals of the Mists Arenanet Points.png
You've completed the Underground Facility fractal inside the Fractals of the Mists.Rabsovich's worst nightmare. 1 Fractals Arenanet Points.png
Master of the Molten Ore Fractals of the Mists (achievements).png Fractals of the Mists Arenanet Points.png
Only use four buckets during the boss encounter of the Underground Facility fractal. Defeated the Boss of the Underground Facility Fractal While Only Using Four Buckets Arenanet Points.png
Stealth Bombers Fractals of the Mists (achievements).png Fractals of the Mists Arenanet Points.png
Use stealth to bomb the reinforced door without triggering any security turrets or contractors within the Underground Facility fractal. Destroyed the Reinforced Door Without Alerting the Locals Arenanet Points.png
Carrier Cacophony Fractals of the Mists (achievements).png Fractals of the Mists Central Tyria mastery pointArenanet Points.png
You made it through Rabsovich's onslaught without dying while inside the Fractals of the Mists.Not part of Rabsovich's plan. 1 Challenges Arenanet Points.png





Entering the fractal
Dessa: Can you (static burst) Hello? The signal (static burst) interferences (static burst) higher ground. But (static burst) are everywhere (static burst) hear me? Higher. Ground.
Fighting the dredge champion
Champion Rabsovich: To battle!
Fighting the Legendary Dredge Power Suit
Legendary Dredge Power Suit: Now you die!
Legendary Dredge Power Suit: Fear the collective!
After defeating the final boss
Dessa: There! Finally, a solid signal. Everything looks stable, too. You can depart when you're ready. So, did I miss anything?


  • Which path you had to take (bombs or guns) used to depend on the fractal level, but it was made random in the 13th December 2016 update.
  • Excluding Rabsovich, Blind does work against the dredge in this fractal, unlike dredge in other areas of the game.
  • Long lasting Protection and Regeneration can be stolen from some dredge.
  • Long lasting stealth, such as from Shadow Refuge or Ash Legion Spy Kit, is useful for activating the control panel during the first phase.
  • When fighting the Powersuit reflection skills can bounce the bombs back at it, however the reflected bombs deal no damage to the Powersuit.
  • The Powersuit's and Ice Elemental's heals can be interrupted by simply damaging them if they are affected by the Superheated debuff.
  • Thieves, mesmers, elementalists, and necromancers may teleport up to switch platforms, saving time and maintaining DPS. To do so, don't stand directly under the platform, but a little to one side, targeting the platform edge with the appropriate skill.