Crumble Undead is a magic combat spell that becomes available at level 39. Crumble undead does extra damage to skeletons, ghosts, and zombies. Crumble undead costs 2 Earth-Runes, 2 Air-Runes, and 1 Chaos-Rune. and gives 98 exp. Crumbling Skeletons can give up to 110k magic experience per hour.