Acid Bubble

 You create an acidic bubble at a point within range, where it explodes in a 12-foot-radius if harmed by attacker. It shields the spellcaster (and/or) his/her allies. It goes in a spheric motion, completely shielding them all around. Each creature in that Sphere must succeed on a Dexterity saving throw or take 1d6 Acid damage.

Cantrip Upgrade. The damage increases by 1d6 when you reach levels 5 (2d6), 11 (3d6), and 17 (4d6).