To unlock the dancer quest, you'll have to talk to Molly at the bar after unlocking the ability to become a nun. Molly will randomly ask for your help. The rare enemy will also randomly show up on floor 2 of the temple in the room with the paintings, and on floor 4, in the room with the statues. I'll probably tweak the spawn rate for next update, or add more locations they can spawn.
But I'm glad you're enjoying it.