A One-Round Adventure for 10th Level Characters
Scaled for 10th - 12th Levels of Play
From the introduction:
The githzerai of the Vendulzat Monastery did not succumb to enslaving other sentient beings much like the mind flayers of Xoriat without help. This corruption at the heart of their society is none other than Khalecterios, an illithid who succeeded in infiltrating the group of escaping slaves with the intent of corrupting them and eventually bringing them back to Xoriat, and possibly aiding in the return of one of the Daelkyr lords imprisoned in Khyber.