Wither

Target must succeed on a Wisdom saving throw or you can change its age by 1d4x10 years and it takes 2 psychic damage for every decade it changes age by. Additionally, its wisdom modifier loses 1 for every decade younger the spell makes it, and its constitution modifier loses 1 for every decade older. 

You may not change the creatures age below 0. For every decade past the maximum for its race, the creature receives 1 level of exhaustion. 

This spell fails on creatures immune to the effects of aging. 

On its turn, if the creature succeeds on a wisdom saving throw, the spell ends early. When the spell ends, the creature's age and modifiers return to normal.