Aspis Prison is an underground arena with stone walls, magma, an elevator, and numerous skeletons. It was one of the game's three original arenas and has remained largely unchanged.
In-game description: TRESPASSERS WILL BE PUNISHED AFTER THE RISING MAGMA AWAKENS THE UNDEAD WARDEN.
- The magma reaches the lowest tile about 40 seconds after the start of the game
- The magma deals 20 damage per second to a player who stands in it
- The Warden appears one minute after the start of the game
- The Warden fires one projectile at a random tile every 25 seconds
- Each projectile deals 10 damage for a direct hit, and is capable of dealing a small amount of splash damage
- There's no way to kill The Warden. Once he appears, he stays until the end of the game
- Aspis Prison is the only arena that loses one of its tiles over the course of the game, which happens when the lava rises above the lowest tile
- Aspis is also the only arena with a tile that moves (the elevator tile)
- The developers were very deliberate when designing the elevator to minimize the risk of motion sickness when standing on it
- You used to be able to see the sky through the bars on the Prison's ceiling, but now it's blocked