Time Knife

You create four daggers in your space. They float in the air and orbit you for the spell’s duration. When you cast the spell — and as a bonus action on each of your turns thereafter — you can expend one of the daggers, launching it toward a target you choose within 120 feet of you. Make a ranged spell attack, on a hit the creature takes 3d6 force damage. For every dagger that successfully strikes the same target, it increases the damage die by one size up to a maximum of 3d12.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the number of daggers created increases by one for each slot level above 3rd.