Bubbling Blood

You bite down on your tongue, causing blood to pool in your mouth. You use this blood to blow volatile bubbles about head sized at your enemies. Make a spell attack against any creature for each bubble you blow, the bubbles do not have to be blown at the same target. Each bubble does 2d8 radiant damage. 

This spell lets you blow 1 bubble at 2nd level, increasing the number of bubbles by 1 for each level cast beyond 2nd.