Wall of Bone [Revised Edition]

Details

Defender (This creature can’t attack.){B}: Regenerate Wall of Bone. (The next time this creature would be destroyed this turn, it isn’t. Instead tap it, remove all damage from it, and remove it from combat.)

The Wall of Bone is said to be an aspect of the Great Wall in Hel, where the bones of all sinners wait for Ragnarok, when Hela will call them forth for the final battle.