In the aftermath of World War Two, Russian soldiers arrested and hanged 5 Nazis for war crimes. After the death the Arkannone (also the Lords of the Gun) offered the souls to be their agent on Earth, and they accepted. Then they were transformed into a horrific ten-armed demon Mawzir who was sent to Earth to fetch artifacts for his masters.
This brought it into contact with Selina Kyle and Tommy Monaghan whose soul they've tried to claim. He rejected them and almost killed Mawzir. The Arkannone brought him back to Hell just to reform him. Later Tommy successfully destroyed it with the Ace of Winchesters - a magic rifle that Mawzir was first sent to obtain.
Mawzir appeared again when he was sicked on a Checkmate Testing site by Amanda Waller. Although it was stopped, the consequences of his actions were devastating.