Arunai

From publisher blurb:

The arunai are angelic spirits who serve the forces of good after they've passed into the ethereal plane. Arunai do not array themselves in fixed form but can freely change their form. This power can be lost if abused or used for ill reasons. Arunai are immortal when the physical body is destroyed the spirit form wanders houseless and powerless until they are either able to regain power substantial enough to retake physical form or are restored by their corresponding architect.