he is a Fallen. He is a demonic being and combat wizard that was responsible for invading the city of Faltra and attacks it from inside while the army attacked from the outside, for that it used Galluk.

Spoiler

Gregore was the number one sorcerer in the Man-Eating Forest. He can fight both in hand to hand and magic. Extremely arrogant. He faced Emile, who he almost killed, but was defeated by Diablo.