Nukte

From Legonia

Main god of the Ystel people.

Nukte is a legendary being, appearing as a Phoenix that can transform into a human form. He has only appeared once on the Island Ystel and teached the Ystel people about magic. For this, he is worshipped as their savior and they pray for his return, which would eventually come once the Red Beast destroyed the entire Island. It was foretold that Nukte would arise at that time and fight with the Red Beast, and both would die. With Nukte's death and the destruction of the island, the end of the entire world is symbolized in Ystel tales.

Nukte doesn't appear in other religions so there's no specific demongod known. As opponent the red beast is accepted though it's unclear if both, one or any of them are real gods per definition. While the bird is its symbol, Nukte could be probably an ambassador or incarnation of Airos.