Arc Lightning

9th-level evocation

Casting Time: 1 action

Range: Self (60-foot cone)

Duration: Instantaneous

Components: S

You extend your two hands, or your spellcasting focus, and waves of extremely bright, dancing arcs of lightning flow out of you in a 60-foot cone. Each creature in that area must succeed on a Dexterity saving throw or take 20d6 Lightning damage and become stunned for 1 minute, or half as much on a success and not being stunned. An affected creature can repeat this saving throw at the end of each of their turns, ending the effect on itself on a success. A creature reduced to 0 hit points by this move is reduced to a pile of fine, gray ash.