Visage of Hadar

you cause a creature to see the true form of Hadar the dark hunger, the creature takes 20d8 psychic damage and must make an intelligence saving throw, on a success the creature must roll on the short term madness table, on a failure the creature falls in to a catatonic state and is incapacitated, the creature can remake the saving throw every 30 days, ending the effect on itself on a success

a creature killed by this spell has its soul devoured by Hadar and cannot be revived by any means short of a wish spell