As to the Baba being a low spawn rate, I have been trying to get it for a long time now (Think years) and had resorted to popping in checking and recalling sessions of anywhere up to 100-200 times per session (yes very boring). At a low estimate I have 5k+ times that I checked. (As a note I am still missing 1 Rare Encounter: The Knight's Fall on Heroic.) I still have the Epics to work on.