Annihilation doorway

An annihilation doorway was a type of dread doorway whose entrance would utterly destroy any creature that passed through it. The only way to reverse its effect was through divine intervention.

Appearance
Annihilation doorways weren't actual doors, but more the frame of a passageway, often carved in horrifying decor. For example, one could be shaped in the head of a demon with the opening going into it's mouth. This opening acted as a vertical, planar sphere of annihilation, appearing as a pure black void.