The Horned Rat is the supreme god of the Skaven, and he brooks no other gods before him. Though not affiliated with the Lords of Chaos, the Horned Rat is almost certainly a distant relative of those foul, nebulous beings. He represents all things the Skaven are, or wish to be. Undying and eternally scheming, this cunning deity patiently awaits the day of the Great Ascendancy, when his children will swarm across the face of the world, devouring it from within. Entropy is his mantra; decay is his stock in trade. All things must rot, figuratively or literally, and the Horned Rat and his offspring are the worldly reality of this simple truth.
All Skaven revere the Horned Rat. None question his existence. Such respect is a product of fear, for the Horned Rat’s eternal hunger does not discriminate between his vermin children and the dwellers of the surface world. A devout Skaven utters small prayers to the Horned God throughout the day, each prayer being a verbal slice of hate, envy, or malice. These prayers are answered often enough to give the Horned Rat validity in the minds of his adherents, even in cases when divine intervention is obviously not involved.
Blood sacrifice is common in the day to day worship of the Horned Rat. The Skaven fear that if the Horned Rat’s appetite is not satisfied, he will devour his children instead. The form of the sacrifice—a slave, Skaven or otherwise—is not as important as the sacrifice itself. There is no specific doctrine that governs who or what must be sacrificed. The sacrifice itself is enough to sate the Lord of Decay for a brief time. Young victims are considered to be the most potent sacrifices for the Horned Rat, while the blood of the aged and infirm is less desirable.
The number of sacrifices made to the Horned Rat by his followers varies considerably depending upon their need. In times of war, the number of daily blood sacrifices can be staggering, sometimes numbering in the thousands in the great Skaven cities of Skavenblight or Hell Pit. The Skaven also increase the number of daily sacrifices if they fail to secure victory in battle, or suffer some other embarrassing setback. The Grey Seers preach that victory cannot be won if the Horned Rat is unsatisfied with his minions, and thus, any defeat or failure is a sign that he must be appeased.
Religious services are constantly held by the Grey Seers in honour of their sinister god. All Skaven are expected to be present at a mass at least once a day, even though no formal records of attendance are kept. Those who do not attend services open themselves up to all manner of criticism, including accusations of heresy, treason, and atheism. Influential Skaven warlords contract their own spiritual advisers from the ranks of the Grey Seers, and these priests for hire give private services to their employers and their households.
- Warhammer Fantasy RPG 2nd ED -- Children of the Horned Rat (pg. 42-43).