The Fallen Piston is a boss that was added on December 28, 2018.
Fallen Piston has a gray circular base with a swarm drone spawner in front, a Trapper turret at the back, and two more swarm drone spawners to the sides.
Fallen Piston has low speed and medium health, using its trap launcher to propel itself forward. Its traps are strong, they have high health and damage, but they do not help the boss much. Its swarm drones are relatively weak, they have medium damage, along with low speed and health. It is also the only boss in the entire game to shoot grey traps.
Spawns by a randomizer.
Fallen Piston is not a strong boss, instead, it is one of the weakest, and killing it should not pose any problems. Any tank should keep a longer distance with the boss, to ensure swarm drones will line up and your ammunition will be able to eliminate them all. Machine Gun branch will have no problems in killing this boss. Drones are not very helpful, as you will get overrun by swarm drones. Out-penetrating Fallen Piston is not hard, so do not stop shooting it. If another player attacks you, retreat and eliminate the player first.