Accursed

Utilizing ancient Agarthian technology, the rune-master and Archon Illaron began his experiments as early as 1450AC. Throughout the years many different rituals were devised- from breeding and mutating newborn human children in bio-pods, to taking the scalpel to mature magi. The ultimate aim was to create a powerful sub-race of humans, loyal to their demon masters, by mixing demon flesh with their own human bodies - a hybrid breed, in a sense.
Approaching the 15th century, the methodology was polished and the ritual had even been shared to allied Archons. It was determined that the most reliable (and potent) technique was to thrall those with the occult already well developed in the dark arts, suited for the enhancements that the mutation brings.
* The ritual requires a powerful demon with advanced occult-based abilities to conduct it, as well as a rune-writer to inscribe the runes. The enchantments are extremely complicated, but can be replicated with study and skill; the runes are embedded onto the Archon as well as the subject. Lesser demons (NPCs) are used as a sacrifice to fuel the occult energy required. By the time the ritual is complete an exchange of flesh has occured from the Archon to the subject, granting them the mutation and altering their magic circuits - loss of former magics to make way for the advancement in occult is common.
* Accursed are struck with incurable occult madness. The destructive urges of the occult are at a peak, and the more they tap into the nature of the dark art, the stronger they become. While they can deny the commands of their Archon, they often feel a sense of kinship with them, as the mutation comes directly from the flesh of their sire.
* Physical mutations occur, and sometimes accelerate as they age. This varies as much as the bloodlines of demons do. Minotaurs, arachnid features, scaled flesh... They always bear resemblance in form to their demon sire.
Mechanics: The ritual may be conducted by an Archon and tier 1 runesmith. The subject can refund two spell trees, and then they receive the racials (which they must buy into, naturally). The subject must be at least 160RPL and heavily invested in occult magic. The magical essence of a spire shard is required for the ritual, and most Archons are only capable of pacting with one Accursed.