Ourobori are used with the Enchantment skill, and always come in pairs. When Magi enchant, they place the commodities in one ouroboros, and the item to be enchanted (if applicable) into the other. The enchantment ritual is performed and then, if the enchantment is successful, the completed item will appear in the ouroboros that did not contain the commodities. If the enchantment is unsuccesful, both ourobori will snap shut, destroying everything inside them.
Ourobi are fashioned in the form of a snake eating its tail.