Arcane cannon

A large glowing ethereal cannon appears on your arm and shoot a boulder at one creature of your choice. You will have to roll a strength saving throw. If you succeed, nothing happens and the cannon fires. If you fail, take 1d8 damage blugianing damage.  D20 to hit, you need to roll above the targets armor class.  On a hit deal 3d8 blugianing damage and it is stunned and prone.

At Higher Levels. When you cast this spell deal +3  blugianing damage.