Eternal Eon

You cause a creature to experience the contradicting notion of eternity.

Choose a creature within range - the target must make a Wisdom saving throw, with advantage if they have more than half their hit point maximum remaining. 

On a failure, the target takes 20d8 Psychic damage, and its mind starts to reel. A creature with its mind reeling experiences time as if it were slowed down to eternity - for each second that passes, the target experiences 1000 years. The target has disadvantage on all ability checks, is Paralyzed, and its Intelligence score becomes 1. At the end of each minute that passes, the target may remake its saving throw, ending the spell on itself on a success.