It is called the dark beyond. You start it up and get to the end where the ghost says "We have awoken the hive."From there you kill the thralls but keep the knight alive. Once you killed the thralls you wipe.
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I'm not sure what you're trying to do here, but that has been a go-to spot for many Guardians since Week one. For bounties, mostly, but now gunsmith rep guns, and exotic sword quest kills. Many more uses. There is no way to say this without sounding like a dick, but if you haven't been using this mission for something, you haven't been making the most efficient use of your time.