Arcane Cannon

You cup your hands at your chest and begin focusing raw arcane energy into a sphere in your hands, charging up for a large attack. Once released, a massive beam of pure arcane energy is projected out from your hands. All creatures in the path of the beam must make a dexterity saving throw, suffering 10d8 force damage on a failed save or half damage on a successful save. Any creatures that are reduced to zero hit points are disintegrated.

You may also choose to hold the attack and continue charging it. For every round that you charge it, add 1d8 to the damage of the attack and raise the save DC by 1. You must remain stationary and maintain concentration until the beam is released. While concentrating, you cannot move or take actions, bonus actions or reactions, otherwise concentration is lost. If you lose concentration, you lose control of the raw energy in your hands and it explodes in a 15ft radius sphere centered on you. In this case, all creatures inside the radius must make the dexterity saving throw or take the appropriate damage (the caster automatically fails).

At Higher Levels: When you cast this spell at 8th level or higher, you may choose to teleport into melee range with a single target within 30ft and release the energy in a single punch. Make a spell attack roll and subtract 5 from the result as you struggle to direct the immense energy in your fist. On a hit, the attack deals the maximum possible damage on the dice, and the target is knocked 30 feet back and falls prone.