Neither. They're actually new missions but each of them are shorter than other missions. But after those, the quests will just be killing unique hive ultras. Although all of them are just wizards/hive/acolytes ultras with a buttload of health and minions. Their names are different from normal hive ultras. "The eyes of crota" (Three acolytes) "The hand of Crota" (A knight) and I forgot the other but it was a wizard I'm pretty sure. After that, you're done with the quests and you can do the strike.