Caelum's Thunderbolt

Clouds swirl as they form above a target in range before a thunderbolt strikes down at them. The target must succeed on a Dexterity saving throw or take 1d8 lightning damage. If the target fails their saving throw, all creatures within 5 feet of the target must succeed on a Dexterity saving throw or take 1d4 lightning damage.

The spell's damage and secondary damage increases by 1d8 and 1d4, respectively, when you reach 5th level (2d8 and 2d4), 11th level (3d8 and 3d4), and 17th level (4d8 and 4d4).