Of course he relies on the elements of fire,water,thunder,earth,wind,light and dark so his spells use those elements. He only get's two shots before it changes back however.

Fire for instance he'd shoot at the sky and a meteor would fall from it. Not an extremely large one about the size of two hummers basically.
Wind would be a small tornado or a torrent of slices with the wind itself.
Thunder would be a lighting storm that would strike three places.
Earth would be multiple pieces or a change in land, instead of one boulder three to four, a small chasm opening something along those lines.
Enough to try and gain an advantage but nothing that could cover an entire battlefield basically, it would either be one large attack or multiple smaller ones since he can only fire six elemental shots. If it's netural it just fires a large focused beam of cylinder energy but he uses both bullets for an attack like that.
I'd say the strongest use would be if he mix two elements together but it would get rid of his rifle in the process and he can't summon it back for a bit. (A few post, three minimum)
Does that help?