Breaching the Veil

You expose a target to unfiltered contact with an extraplanar being. Contact with this extraplanar intelligence can strain or even break their mind. When you cast this spell, the target makes an Intelligence saving throw. On a failure, they take 10d8 psychic damage and are insane. On a success they take only half damage. While insane, they can't take actions, can't understand what other creatures say, can't read, and speak only in gibberish. A greater restoration spell cast on them ends this effect. They may repeat the saving throw at the end of their turn. Upon a success the effect ends.