Void Blight

Planar Curse
Void Blight is a magical disease placed on a creature that has been to The Eternal Void.

Those who spend too long in the Eternal Void will eventually begin to take the form of a servile, monstrosity. Those who have made a pact with the King of the Eternal Void, Zenituul, or another powerful being native to the Void, can control and summon these creatures.

At the end of a long rest within the Eternal Void, a creature who is not native to the Eternal Void must make a DC 10 Constitution saving throw. On failure, the creature contracts the early stages of Void Blight. If the creature fails 3 non-consecutive times while having not long rested outside of the Eternal Void for a number thrice that of the number of failed con saves, they fully contract Void Blight and immediately die. Lesser Restoration cannot cure Void Blight, but casting it does remove one of the failed con saves with each casting. For each con save made, both failure and successful, the DC increases by 2.

Tentacles writhe in and out of the bodies of those afflicted, a black gas spews from the mouth, and their blood turns to a odorless black goo.

When a being who has been tainted this far dies outside of the Eternal Void, their body and blood fades away into black mist, returning their soul and body back to the endless torment of limbo in the Eternal Void, awaiting summon again.

Once a being is afflicted, nothing short of Divine intervention or Wish is known to remove the effects. A creature that dies to the effects of Void Blight cannot be revived with anything other than a Wish spell or True Resurrection.

Effects
Creatures affected become aberrations and gain the following traits: Immunity to necrotic damage