It's an exotic mission, very long one. You need 2 players to do it and CONSTANT via mic communication, cause it's basically a mini raid. No other way to do it. First you need to do all overthrows in all 3 locations, after every 4th wave boss kill a seeker will spawn, a hive wizard, you kill it in eg Landing, then in Blooming, etc. Once you do all of that you will see a green light on the map. Go there, you will collect one memory, other player will collect second memory. Then the mission will appear. The mission is also very hard, I just watched to day 1 raiders beat it with 2 mins left. Good luck to the rest of you, who don't live to play this game. You will never get even one random exotic class item lmao