Ebon Lightning

Ebon lightning streaks from your fingers as you cast this spell. Each creature in the line must make a Dexterity saving throw. If the saving throw fails, the creature takes 8d8 lightning damage and loses (expends) its highest-level spell slot for no effect. On a successful save, the creature takes half damage and doesn’t lose a spell slot. Creatures with innate spellcasting lose one use of their highest-level spell instead.

Enhancement: For each spell slot used higher than 7th level, the damage increases by 1d8.