Kalah

Kalah was a gnome illusionist who worked in a circus that toured Amn and Tethyr in the 1360s DR.

History
He grew bitter at being made fun of and, when the circus stopped at Waukeen's Promenade in Athkatla, Amn, in 1369 DR, he used powers he had gained from an unknown source to turn the inside of the circus tent into an unreasonably large world of illusions in the middle of his act. Some people trapped within were killed and others were seemingly turned into various monsters, like Aerie and Quayle. The illusory world was also populated by shadows and werewolves, some of which were real enough to hurt people they attacked and others of which only became so if they were attacked back. Kalah himself appeared as an ogre-sized figure more impressive than his usual self.

If Gorion's Ward and party entered the tent while in Athkatla, they might've saved some of the people trapped within and defeated Kalah, turning everything back to normal except for those people who seemed to have simply disappeared after dying. Before dying, Kalah shouted "This is not what was promised to me!".