Certain creatures can cling to the walls of the dungeon, allowing them to pass over otherwise impassable terrain as long as they stay orthogonally adjacent to a wall (they cannot cling to only a corner).
Creatures that can cling to walls:
- Prior to 0.15, players could cling using Spider Form or boots of the spider.
- Wall-clinging was added in 0.8.
- mon-util.cc:851 (0.21.0)