"Maghda is a fool. I will raise an army of souls from these primitives and chain them to my invincible will. Yes, with these heathens at my command, the kingdoms of the world shall bow to the might of... The Lord of Goats! I may have to work on the title a bit more."— Dark Cultist(src)
He is always found in Southern Highlands (only in Campaign Mode), at the same location (a small ridge in the easter part of the map), chanting over the four Kharza mummies. When approached, he will exclaim that the player is doomed, and then raise four ghostly Khazra Brutes to aid him in combat.
Lord of Goats himself is an ordinary Dark Cultist with no extra abilities. Upon death, he drops A Summoner's Journal, revealing that he had a plan to conquer the world with an army of invincible undead goatmen. While in game he is named only "Dark Cultist", the Lord of Goats is his self-proclaimed title.