I invited my noobs friend to patrol on the cosmodrome when he was low level. I led him to the dark room where you killed the hand of crota or whatever the thralls name was. As we were clearing the normal hive, I ran over and killed the little thrall in the corner, triggering the high levels to spawn in. Then I ran like hell as he was murdered by them and laughing when he screamed out in realization that the high levels had spawned in.