That's because it's an angel... that will bind Satan into his pit prison during the future 1,000 years of Revelation 20...
Rev 20:1-3
20:1 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand.
2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years,
3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season.
KJV
Most likely, that will be the Archangel Michael that will do that binding of Satan into chains.