Tomb of Doroklohe
Tomb of Doroklohe is a monsters-only spell which surrounds the caster with temporary rock walls on all sides, giving him time to recover mid-fight without fear of assault. Unless your character has some means of digging through rock, the caster will be able to regain significant amounts of HP by the time the walls dissipate.
The walls created by this spell may not fully surround the caster if there are certain dungeon features in the spaces they would normally fill, and any items in those squares will be displaced (possibly inside the tomb).
The following monsters cast Tomb of Doroklohe:
History
Tomb of Doroklohe was a level 7 Conjurations/Earth Magic spell the player could cast in Dungeon Crawl, but it was removed from the Stone Soup version of the game. The effect can still be duplicated via the Tomb card.
Before 0.11, the walls created by this spell were permanent.