Kamehameha

You learn to harness the energy in your body, condensing it into a large energy blast. You gain the Kamehameha action.

You can expend one ki point to create a large blast of energy from your hands. Every creature in a 60 ft. long, 30 ft. wide line must make a DC 26 Constitution saving throw. At any level under 6, the Kamehameha only deals half damage.

If they fail they take 57 (7d10+18) radiant damage, but if they succeed they take half damage. You can increase this damage by 29 (2d10 + 18) for every additional ki point spent, increase its length by 30 ft., and increase its width by 15 ft.