Arcane Dagger

You form a mote of arcane magic into a dagger.

As a bonus action, you create a magical dagger. It acts as a normal dagger, except you add your spellcasting modifier instead of strength or dexterity to attack and damage rolls, it counts as magical for avoiding damage resistances and immunities, and it dissipates after making a thrown attack with it 

The damage the dagger deals increases by 1d4 at 6th level (2d4), level 12 (3d4) and level 18 (4d4)