Summoning Key

The Summoning Key is a mysterious artifact featured in Call of Duty: Black Ops III Zombies. It is featured in the map Shadows of Evil as a quest item. It plays a large role in the map's easter egg, Apocalypse Averted as well as The Beginning of the End.

Summary
The Summoning Key can be found in a crate in the back of a truck in the spawn alley in Shadows of Evil. In order to obtain it, the player must enter beast mode and smash the crate, revealing the Summoning Key.

The Summoning Key is used by the players to complete rituals around the map. Everytime a ritual is completed, the soul of the person sacrificed in the ritual will be trapped within the Key. During the easter egg, the Shadow Man is ultimately trapped within the Summoning Key by the players in an effort to remove the Mark of the Beast on their hands.

After completing the easter egg, a guardian will hand the players the Summoning Key in order to remove their curse, but before they could grab it, the Edward Richtofen from Origins will snatch the Key, saying he doesn't have time to explain and that he has a universe to set right before thanking the crew and leaving through a portal, dooming the Shadows of Evil cast. In the map The Giant, Richtofen will mention to Nikolai that he has an artifact that could be useful to them later on, which is in fact the Summoning Key.