Serpentine Apotheosis

"The method by which the Yuan-ti evolve themselves to become more like their reptilian god-kings is horrific, yes, but worth studying, I should think. We may not be willing to conduct the human sacrifices required but there may be other ways to fuel the magic, and other directions to work towards than a serpentine obsession."
~Grandmaster Jeren, of The Golden Tower

History

The Yuan-ti were taught the ritual of Serpentine Apotheosis by the Saurians, whom they worshiped as gods. They have changed it very little from the original formula, and resentment engendered by their continued practice of it lost the race their independent territories.

Execution

When Mizov passes over Akiri, the sacrifices are led up the stairs of the pyramid. Beforehand, they must have been compelled to consume what would be an ultimately fatal potion to prepare their flesh. One by one, they are laid out on the altar, and the high priest carves out their hearts. Each heartless body is thrown into the opening atop the temple to the cheers of the onlookers while the supplicant to receive the apotheosis swallows each heart in turn. The ritual must be completed before Akiri is again visible, or the effort and expense is wasted.
After the ceremony, a draught must be consumed by the supplicant that will begin their transformation. This draught can be consumed up to a week after, and the transformation will take a full season of hibernation to finish.

Components and tools

Required for the ritual are: the sacrificial potion, an obsidian knife that has been bathed in ophidian poison, an altar to the god-kings set atop a step pyramid arranged according to tradition, and the ceremonial draught to be consumed afterwards.

Participants

The high priest must make the sacrifices with the blessing of the pyramid's god-king, who need not be in attendance but often is to make the point of who is ultimately responsible for the advancement. The supplicant must stand on the left of the altar, ready to receive the hearts. Unnecessary for the ceremony, Scalykind of the community usually come out to watch for the spectacle and an evolution without an audience is considered a sign of social weakness.
Finally, the ritual requires slaves. Elves are preferred, but humans will do. At roughly triple the number required, ophidians can be used but this is only done in the direst emergency and the numbers required are prohibitive for the window of time involved. The number of slaves required increase the higher up the Pyramid the Yuan-ti needs to go. A mere 30 slaves and 900 GP in treasure are required to evolve from a pureblood to a malision. 100 slaves and 10,000 GP in treasure are required for an evolution from malision to abomination. 2000 slaves and 2,000,000 GP in treasure are required to turn an abomination into an anathema. Additionally, the apotheosis into an anathema can only occur on a Necromancer's Moon
Needless to say, the abominations that can gather the supplies to become anathema are likely already highly accomplished warlords.

Observance

The ritual can and will occur during an eclipse of Akiri by Mizov. Yuan-ti astronomers meticulously track such events so that prominent yuan-ti can be ready for their evolution.