Arcane Augment

Your weapon starts to surge with arcane power, and it lasts for the duration. When you hit a creature with a melee attack. On a hit, the target takes 1d6 extra force damage.

If you kill a creature with a melee attack during the duration of the spell you can use a bonus action to unleash your stored arcane power in a 20 ft. radius Sphere around you. All creatures except you who are caught in the area must make a DEX saving throw. Creatures take 3d10 force damage on a failed save, or half as mush on a successful one. This will consume the remaining duration of the spell ending it immediately.