Bubble Bomb

You create a magical bubble containing explosive arcane energy. You can touch and move this bubble without it popping, and move it up to 15 ft through the air when you create it. You can move it again as a bonus action on each of your turns. When a creature other than you comes in contact with the bubble or you lose concentration on this spell, the bubble explodes and each creature within 5 ft of it makes a dexterity saving throw, on a failure they take 1d8 force damage. 

The spell creates more than one bubble when you reach higher levels: two bubbles at 5th level, three bubbles at 11th level, and four bubbles at 17th level. You can direct any number of bubbles with a single bonus action.