The Witch's Gambit mission is one of many Vengeance quests available in Destiny 2 Heresy Act III ... To identify an encounter in The Nether, take your Ghost out and watch for the 'Star' grey ...

Ghosts are a Guardian's companion in Destiny 2, but during the events of The Final Shape expansion, some of these protectors of Light become lost until you find them. During the "Alone in the Dark ...