World of Adventure 2.0
Hooked Walls Terrain/Trap
The walls of this room have wicked, barbed hooks mounted on them.
Any creature that attempts to move through the wall space (i.e., is pushed or slid from an adjacent square into the wall’s square) is attacked by the terrain/must make a saving throw.
Successful hit/Failed save means the character is immobilized and takes ongoing X damage (save ends both) as they are ensnared by the hooks.
A character under these effects that is forced to move from its square via a push, pull or slide takes an immediate XdY damage, but no longer suffers further effects of the terrain. A character that teleports away takes no such damage and is free of the terrain’s effects.
Combine with creatures that can push or slide characters multiple squares, and tight areas with little maneuvering room.