You have to get Jupiter in the store, and I'd say get on it because Jupiter is powerful in both single and multiplayer modes.

He gives his element marbles attack and health boosts, and that's huge when you're laying down your marbles. His attack range is not better, but he has a definite advantage in close quarter combat. Just try stringing together a few fires together and attack an air. You'll notice a difference in power.

Pick him up if you don't have him already.