a poison brewed to not kill, but to torture indefinitely, created by a powerful lich to use as a way to elongate the life of their servants, while also having them be in too much pain to ever question him. there was once 12 of these potions but after they were distributed between the servants only one remains.

the poison has 5 charges, charges can not be regained and the charges are consumed once a 5th of the potion is consumed.

artifact properties: the poison grants it's drinker 2 minor beneficial properties, 1 major beneficial property and 2 major detrimental properties.
minor beneficial: the consumer is immune to disease and gains a +1 bonus to AC
major beneficial: the consumers strength and constitution increase by 2 (to a maximum of 24)
major detrimental: when you consume a charge of the potion, there is a 10 percent chance that you attract the attention of a god that sends and avatar to wrest the artifact from you. The avatar has the same alignment as its creator and the statistics of an empyeran. Once it obtains the artifact. the avatar vanishes. and the drinker emits a foul and slightly sweet stench that can be noticed up to 10 feet away.

once consumed  the poison will take effect, increasing in severity by how many charges of drink you had
1 charge: the users decomposition slows down while still taking effect, the soul of the creature will still be bound to its body and the body will still be able to function far past the users death, the user will still be able to keep all of their senses, including their nerves, which will feel all effects from the decomposition.
2 charges: the user gains 50hp on the spot
3 charges: the users body and soul can no longer be displaced, the user is immune to spells which would place their body and soul elsewhere including powerful items like the void of the deck of many things, this includes their own spells and any portals they may come across.
4 charges: the user is resistant to all damage
5 charges: the user can no longer die, their soul forever bound to their body in a perpetual state of undead, nothing short of another artifact, the wish spell or divine intervention can kill the user

Notes: Bonus: Strength Score, Bonus: Constitution Score, Bonus: Armor Class, Immunity: Disease, Resistance: All