The Sahuagin Ending is an ending in Prisoners of the Elder One. It occurs after using the Transfigurative Orb on either the Water Spirit or Aya when she is next to her.
The Water Spirit senses the magical artifact's power, turning it towards Erik and turning him into a fishwoman, or a Sahuagin. She attempts to fight the Spirit, but she takes Erik's voice as further punishment, turning her into a servant and living in the pool in the Garden.