Curse of Yondalla

The curse of Yondalla was an especially powerful abjuration/alteration spell, granted only to followers of the hin deity Yondalla and reserved only for use against creatures guilty of destroying a halfling community or slaying innocent and defenseless halflings.

Effects
When cast, any creature or person affected by the spell was stunned and, over the course of the next minute, reverted to a state of infancy, first slowly and then faster. Undead creatures without any sort of divinity were immediately destroyed while extraplanar creatures were banished to their home plane and unable to return for up to 100 years.

Usage
The resulting children were then brought up by a halfling community or the priest who cast the spell and taught to respect halflings. If the child was one of an inherently dangerous species, it was sent to foster parents who would be able to handle such a creature and raise it to have morals and ethics.

The only way to reverse the effects of this spell was for the cleric who cast, or one more powerful than they, to cast a remove curse spell upon the infant. Otherwise, only a wish could dispel the effects. Destroyed undead creatures could also be brought back, but a banished outsider similarly required a successful wish spell or some form of divine intervention to return to Toril.