Ah, a very cool demon, Bune/Bim shows up in the form of a three-headed dragon–one dog head, one gryphon (and here I reiterate that gryphons have eagle heads) and one human head. He speaks in a voice so melodious that even the Dead listen to him.
Bune can command the dead, Evil Dead style, so that you can command them, too. (Can I stress what a very bad idea that is?)
He can make you rich, wise, and eloquent. He’ll also answer any question you ask.
He has two lamens, that he must obey. The Goetia advises using the square one, not the curly one.