Deneb's key is a silver key with a simple design. The bow is designed similar to a swans wing and tail feathers with the crest in the middle. The blade is of simple design, shaped like a swan with several blue orbs.
While in possession of the key, a Celestial Spirit Mage may be able to summon the Swan Deneb by reciting the quote, "Open Gate of the Swan! Deneb!". This summons Deneb, who is capable of using Lightning Magic to strike his target(s).