Impurity Cube is a stationary entity that spawns when the player defeats the Wall of Flesh. It acts similarly to a Purity Cube, but it corrupts tiles instead of purifying them. Only one can exist at any point and another one won't spawn if one is alive. If there is more than one Impurity Cube in the world, all but the first one spawned instantly despawn.
Unlike Purity Cubes, the Impurity Cube does not die on its own.
All damage inflicted on the Impurity Cube is divided by 10, making it tedious to deal with.
It always spawns in the centre of the world, slightly above lava level underground.
If an Impurity Cube is killed, it will not respawn upon world loading.