For the Cant word, see Bub.
Bubonix is a mighty Yugoloth lord (an Altraloth), master of the Tower of Incarnate Pain in Carceri. He is not as powerful as the Oinoloth or the General of Gehenna, but he's a powerful force in his own right. He is served by Cholerix.
Dragon Magazine Annual #2
The really important portal key is always completely unavailable, inconceivably expensive, or utterly humiliating.