Servant of the Hand
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Search the room for a small alcove with a pile of garbage; killing everything first is advised as the radar will help. Inside is the Servant curled up, partially concealed. He will get up when disturbed and attack. Killing him will summon multiple greenish portals, from which more Servants of the Hand appear, along with Cursed Thrall. The Hand of Crota, a Hive Knight Major wielding a Cleaver, will also appear. The Thrall will keep spawning until the Hand is killed. Being killed will reset the process, and the original Servant of the Hand will not reappear, forcing a reentry.
List of appearances