The walls of the cell regenerate by a fast downwards basalt generator, and the floor also regenerates. The roof is too high to reach, but it regenerates too. The prisoner respawns via a two-chambered system in the ceiling, and there is water on the floor to prevent fall damage. Bread and visitors also come through the ceiling. A conduit prevents the prisoner from drowning. A guard can look at the cell through a composter glitch.
Outside Defence
There are many elder guardians in specific areas all around the prison, which constantly give Mining Fatigue 3. On the walls and roof of the prison, there are layers of water and lava separated by obsidian, as an attempt to slow down withers.
More Security
There are hoppers under all beds in the visiting process, and guards can drop in at various points to try to stop problems. Doors in the guard areas are protected by keycards, making it hard for invaders to move around as easily. There is an AFK fishing station to ... get fish.
