Diep.io Wiki
Diep.io Wiki

The Fortress is one of the Arras.io Tier 4 Tanks that may upgrade from the Cruiser at Level 45. The Fortress may no longer upgrade as it is the end of its upgrade line. The upgrade key for this tank is H.


The Fortress has a circular base with 3 inverted Spawners (same as those of a Cruiser) and 3 Launchers (same as those of a Trapper). Each Spawner is 120 degrees from the other, and the same applies with the 3 Launchers.


The Fortress's three Launchers shoot the same size Traps as the Trapper. Its three inverted Spawners shoot the same Drones as that of the Cruiser.


  • Strong Against: most tanks in a 1v1 situation if skilled.
  • Weak Against: high DPS tanks, tanks with concentrated firepower.

As the Fortress

  • Because of the many projectiles it shoots, the Fortress is exceptional at crowd control. The Drones can take out any low health or unsuspecting tanks while the Traps protect the Fortress itself.
  • The Traps and Drones give the Fortress amazing defense and offense capabilities. The Drones are mainly for offensive because of their speed and the Traps, of course, are used for defense.
  • Becuase of the Drones, the Fortress can be safely used in a fight. Its Traps will protect itself from any projectile while the Drones attack the tank.
  • High FoV tanks like the Sniper are easy kills as the Traps can block the bullets while the Drones overwhelm and destroy the attacker.
  • Try to spread out the Drones against a Destroyer so they will not be destroyed all at once.

Against the Fortress

  • As a Triplet or Penta Shot, focus on the Drones first. Then move closer to destroy the Traps and any other Drones. Focus mainly on the Spawners and Launchers as the player will not only destroy the projectiles that come out, but also damage the Fortress.
  • A Streamliner can easily cut down the Drones, then the Traps, and finally the Fortress itself with its high reload and constant bullet stream.
  • As the factory use the drones to take down the drones then aim at the side of traps so you take down the traps and the fortress itself


  • The Fortress is the combination of two Level 45 tanks (in both games) - the Carrier from Arras.io and the Tri-Trapper from Diep.io.