Set, or Seth, is being of pure chaos and evil. He is opposed to everything the Pharaonic and Mulhorandi deities represent.
Set is infamous for murdering his brother Osiris and cutting him into pieces. Set murdered Osiris for two reasons: out of jealousy over Nephthys's seduction of Osiris, and in an attempt to seize the rulership of the pantheon, which Re relinquished and Osiris was poised to claim. He continues to struggle with Re-Horakhty for the throne, but he has no interest in an ordered government.
Lower-level clerics of Set operate in secret, hiding their identities and striving to appear as nothing but hard-working, well-meaning citizens. They usually carry Set's symbol tattooed somewhere on their bodies, but do not display it openly or in any other way indicate their beliefs. This is basic self-defense, protecting themselves not just from legal and religious authorities but also from higher-level clerics of Set who might view them as a threat to their position.
As an individual cleric's power grows, he becomes increasingly likely to reveal or even flaunt his position. Male clerics often shave their heads, like other Pharaonic/Mulhorandi clerics, in defiance of the orthodox assertion that they are not true priests. They prefer black armor to white robes, however. High-level clerics often become blackguards.
For the most part, Set's followers meet in hiding, believing that temples simply provide an easy target for Re-Horakhty's paladins and other do-gooders. They worship their master in hidden shrines and caverns. However, large fortress-temples to Set stand in certain remote desert regions, protected by powerful clerics and minions of Set.
Set's struggle with the other gods of the pantheon is about power, not empire. He believes that he is the strongest of the deities in the pantheon, and that his strength makes him the only one fit to rule. He perpetuates this idea of rule by the strong within his cult, where cleric-assassins vie with each other for power and position.
According to Set, whatever a person is strong enough to claim belongs to that person by right. The "divine right" of rulership that Re-Horakhty teaches is meaningless in Set's eyes—rulership should be held by whoever can seize and maintain it. Authority should be respected only insofar as it is powerful enough to enforce its will.
Set appears as a powerful man with a bestial head resembling a donkey, with a curved snout and upright, square-tipped ears. He also has a long, forked tail. He sometimes appears in animal form, as a hunting dog (resembling a greyhound or saluki), a hippopotamus, or a wild boar.
Set was the younger son of the Earth God, Geb, and the Sky Goddess, Nut. Set was the brother of Osiris, Isis and Nephthys and he was also the consort of his sister Nephthys. Nephthys bore him a single child, Sobek.