Arcane bomb

You conjure a magical bomb in a free hand which can be thrown as a free action this turn. When thrown the bomb explodes and each creature within 5 feet of that point must succeed on a Dexterity saving throw. On a failed save the target takes 2d4 fire/acid/thunder damage. If any affected creatures roll a natural 1 for the saving throw, they take double damage.

A bomb lasts until impact or for 3 rounds after leaving the hands of caster.

This spell's damage increases by 2d4 when you reach 5th level (4d4), 11th level (6d4), and 17th level (8d4).