Moss giants are the guardian spirits of Glarial's Tomb, and are significantly larger and stronger than ordinary moss giants. It is encountered during the Waterfall Quest when the player enters the tomb to obtain Glarial's amulet, and must later be killed during the Roving Elves quest to obtain the consecration seed. It can only be fought unarmed, as it is impossible to take weapons, armour or ammunition into the tomb. It causes a magical splashing effect when it attacks, and will occasionally hit with Magic instead of Melee.
After completion of the Roving Elves quest, it can be fought in the Nightmare Zone. Players do not need to be unarmed to attack it there.