The Double Head is a large two-headed serpent that guards "the Sindar's greatest treasure" in the Sindar Ruins located near the White Deer Inn. The monster attacks the party led by Riou and Alex, in response to their entry into the inner sanctum of the ruins. It stands between the party and the bag of Healing Herbs found within the treasure chest at the top of the stairs. Following the defeat of this monster, it is never mentioned again over the course of the game. While the party leaves with nothing of major value, they are able to save Hilda's life with the herbs.
Each of the monster's heads bears a strange pattern on the top of it. Whether or not these patterns represent some kind of rune, or are just different decorations, is unknown. Each of the heads is capable of a vicious bite attack, and can even perform it simultaneously. Double Head can also summon a rain of frozen energy or liquid fire from the sky, fueling speculation about the monster's apparent "Rune patterns".