Cone of Madness

You attempt to shatter the minds of creatures in front of you as you interpose your knowledge of the Unknowable into their minds, driving them to madness. Each creature of your choice in a 60-foot cone must make an Intelligence saving through. On a failed save, a target takes 6d8 psychic damage and is stunned until the end of its next turn. On a successful save, a target takes half as much damage and is not stunned.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 5.