Awakening of Evil

Hello everyone. In my map, in the first mission, Death Knights have been replaced by, or appear alongside, Death Harbingers, just like in the "Pack Leader" map. They have 300k HP and 7000 attack. But in "Pack Leader," they are part of the scenario, and you get Knights to kill them. Now, they've appeared on other maps, and I don't know if they're part of the scenario or just a bug. Specifically, a group of 40 of these Death Harbingers, along with Knights, guards one of the artifacts of darkness (a cloak, to be precise).