While King Michael and Bear Claw attacked from the sides, Eric attacked from the back and Mogranius attacked from the front. This all happened in almost the same seconds, so you can consider that all Fire Controllers attacked almost at the same time.
There is a reason why Mogranius is in front of the Army and Eric is in the back of it. For a start, it would take a few seconds longer to recover from an attack that came from behind. And obviously, King Michael wanted a highly powerful person doing the damage.
Eric can burn harder and longer without dropping to the ground because of Stamina. Mogranius was set in front, because he is known to be more slick, more agile.
He can avoid attacks which are the most common when facing an Army head on, and he can definitely catch a bit more attention so the other three Fire Controllers can compress the enemy Army better from all sides.
