Casting Bones - same as that used by witch doctors.
This powerful magic item was created to augment Alienists, a prestige class in the Tome and Blood.
Circlet of Amplus Ater Iris meaning “Circlet of The Great Dark Messenger” (Amplus - great, important; Ater - dark, malicious; Iris - messenger of the gods. Thought by some to mean Nyarlathotep)
The PCs see a large oak tree, a curious species of yellow and black butterflies swarm around it. Upon further inspection they find that the tree is hollow and that there is an underground cave in it from which the butterflies appear. Will they inspect this strange cave?