These are level 50. Several locations that they spawned. Killed 4 with no page drop.
They are LB to 64, DB to 52 to 60 toons. They are social and will gain assist from others.
Suggest pulling to the walls or away from others. A tracker is basically required. Spawn time appears to be 15 mins or so but did not keep good records. Only one seemed to be up at a time and each spawned in a different place.