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Diep.io Wiki

Not to be confused with the Diep.io Necromancer, which has a near identical design.

The Underseer is one of the current Tier 3 Tanks in Arras.io that branches off from the Director. The Underseer may further upgrade into the Necromancer and the Maleficitor. Its upgrade key is I.


The Underseer looks like the Necromancer from the original Diep.io. As such, it has a square tank body as a base and two Spawners on its sides.


Upon upgrade, the Underseer replaces its Drones with Necro Drones, which are square Drones weaker than its triangular cousins but possess the unique ability to convert neutral Squares into one of theirs by colliding with them. The Underseer's Reload is very slow (~2 Drones / 9 seconds). Each spawner has the lowest reload in the game, more than twice as long as an annihilator's. Notably its 7th Stat, though displayed as "Respawn Rate", does not actually increase respawn rate but increases Max Drone Count. Its effect is as follows:

Stat Points Max Drone Counts
0 14
1 17
2 19
3 21
4 22
5 24
6 25
7 26
8 27
9 28

The Underseer has 25 1/4 grids of horizontal FoV, same as the Overseer.


  • Auto Fire by pressing E.
    • On = Drones will move towards the player’s cursor.
    • Off = Drones will attack any entities which are “hostile” (Polygons included) automatically if no buttons are pressed. If there is nothing to attack, they will form a pseudo-shield around the Underseer.
  • Shift/Mouse (Right/Left buttons).
    • Holding the left click, or space, on the mouse will make the Drones move to the player’s cursor.
    • Holding right click or shift, causes them to move away from the cursor, holding it will move the Drones in the opposite direction of the mouse’s position as to where the cursor is.
    • For example, holding right click north of the Underseer will move the Drones south.


  • Strong Against: anything with low DPS and other Drone classes with weaker or less drones, if the Underseer is not low on Drones.
  • Weak Against: anything with high DPS and every hostile entity if low on Drones.

As the Underseer

  • Players should use the two Drones spawned by the Underseer's Spawners to get more Drones. If these Drones are killed they will not respawn via the Spawners but the two Drones already provided will)
  • One good tactic is to try and surround the hostile entity with Drones so they have less chance to escape.
  • If the Underseer is low on Drones, they should flee from battle and find any Squares to infect with so you can go back to the battle. Otherwise the Underseer will be very vulnerable and is open to attacks.
  • Don't pick the Underseer when in Maze Mode, as the limited space for your drones to move about will mean they can quickly disappear from touching maze walls.

Against the Underseer

  • Try and ambush the Underseer when they are attacking another tank. If they have low Drone speed, they don't stand a chance due to the fact that it cannot move it's Drones for protection in time.
  • Tanks with a large Field of View tanks work well against the Underseer, since the player can attack it from a distance while the Underseer is helpless to respond.
  • Underseers low on drones should definitely be your first target when looking for Drone-using tanks to kill, as they cannot do anything other than flee and try to find Squares.
    • Eliminate any and all squares in a convenient radius, in order to decrease the Underseer's chances of defense/offense.
    • You could keep a droneless one as a pet