Arcane Weapon Master

You channel arcane energy into one simple or martial weapon you’re holding. Using a bonus action you can choose one damage type: acid, cold, fire, lightning, poison, or thunder - for one minute you deal an extra 1d4 damage of the chosen type to any target you hit with the weapon. 
You can change the damage type, choosing from the options above using a bonus action.

You can use this ability an amount of time equal to your intelligence modifier and regain all uses of it when you finish a long rest.