Black Dogs

The Black Dogs are strange entities encountered by Group Alpha that resemble black furred canines with golden eyes, golden tipped ears, and a golden symbol of an eye in the middle of their heads.
They were first mentioned by Kasdri Valmorn, who presumed to be either deities or the messengers of such, perhaps pertaining to the Luminaire. When he asked Soren Hightower about them, it was revealed that he had never heard of these entities in releation to the Luminaire or her subservient deity, Nusemnee.
Sirius Greymoon revealed that he encountered one of the dogs on Group Alpha's journey to find a way to enter Adair of Storia's demiplane. He claimed the entity to be rather helpful, and that it helped him find a piece of something he was looking for. 
Factus Formis claims that another one of these entities was guarding the Princess of the Vel'karis, who herself claims that the dog simply "came to her'.