Synaptic Shockwave

You send a roiling wave of psionic energy outward in a 60-foot cone of psionic power, creating psychic storms in the brains of affected creatures. All creatures in the area must make an Intelligence saving throw. On a failure, a creature takes 10d8 psychic damage and is stunned. On a success, it suffers half as much damage and no other effects.

At the end of each of a stunned creature’s turns, it rolls 1d6. Its Intelligence score is reduced by an amount equal to the roll. The creature then repeats the saving throw using its original intelligence score, gaining a bonus to the roll equal to the total amount its Intelligence score has been reduced. On a success, it is no longer stunned. If a creature’s Intelligence is reduced to 0, it dies.

A creature regains 1 point of lost Intelligence after finishing a long rest. The heal, mass heal, regenerate, and wish spells can instantly restore all lost Intelligence. Greater restoration can restore 1d6 points of lost Intelligence.