Lichnee potion

A lichnee potion, also known as a potion of transformation, was a highly poisonous mixture that had to be imbibed as part of an evil ritual to become a lich.

Description
When properly prepared, the mixture was a sparkling black liquid with a bluish glow.

Recipe
The following ingredients had to be mixed together in this specific order under the light of a full moon: 2 drops of pure distillate of arsenic, 1 drop of pure distillate of belladona, 1 quart of blood from a human infant killed by wyvern venom, 1 quart of blood from a non-human humanoid killed by a phase spider, 1 quart of blood from an individual infected with vampirism, 1 simmered intact heart from a humanoid killed by a mixture of arsenic and belladona poisoning, 7 sets of ground-up reproductive glands from giant moths killed within a tenday, 1 pint or more of fresh phase spider venom (less than a month old), and 1 pint or more of fresh wyvern venom (less than two months old). There existed alternative recipes that disputed certain details, such as what kinds of humanoids' blood to use, how old they had to be, and whether or not they were a virgin.

In addition, the soul of a sentient creature whose blood was used in the potion had to be sacrificed to the aspiring lich's phylactery.

Some versions of the lich transformation ritual further called for the potion to be enchanted with castings of animate dead, cone of cold, feign death, permanency, and wraithform.

Powers
The purpose of the potion was to ready the drinker's soul to be placed into their phylactery, while also preparing their body to become an undead vessel that could only be completely destroyed via a disintegrate spell. Ingesting an improperly mixed potion was fatal, and ingesting the magically-enhanced version was irreversibly so.

Some versions of the potion were consumed at the time of a ritual of transformation, killing the drinker and raising them as a lich, while other versions were not (usually) immediately fatal if properly prepared. An aspiring lich generally had to drink within seven days of its creation, and had to finish it all within six minutes. This left the drinker notably paler, and had one of a few nasty side effects: the drinker might fall into a coma for up to seven days, be rendered feebleminded and frail, be paralyzed for up to fourteen days with possible permanent damage to their reflexes, or be rendered blind, deaf, or mute such that only a wish or limited wish could restore them. This was not even including the more than 1-in-10 chance that the potion would simply fail to take effect, which might kill the drinker or just cause them to lose all body hair. After resolving whatever side effects they experienced, the drinker was free to continue pursuing the final stages of becoming a lich, namely by preparing a phylactery. During this time, their status as a proto-lich was always known to them, irrespective of any magical or mundane memory loss, but it was undetectable to others.

If the aspiring lich died before the phylactery was completed, they would be forced to brew and drink the potion again.