Marshall and Mason were both legitimate big play and/or touchdown threats any time a football was in their hands, and they happened to be the best fake handoff duo that I think I have ever seen. There was a wildcat QB taking every snap, he was trusted to throw the ball as well, and he had a Heisman finalist back there with him. If the defense bit on the wrong ball carrier, either one of them was fast enough to be in the secondary before they realized it. If Marshall had the ball, the only way the defense ever knew he was not subject to throw the ball to a receiver they forgot about was once he crossed the line of scrimmage. That was what everyone lining up to defend against them knew.
Marshall was a CB playing QB. He was conditioned to run a lot, and was quite good at it. He was excellent at keeping the play going long enough for an opportunity to present itself, or simply create one himself. I doubt he ever takes snaps at QB for a major P5 program that is not coached by Gus Malzahn or Rich Rodriguez, but at Auburn he was good enough to complete a pass to himself for a big play. You simply cannot coach the instincts that man had. The rest of the offensive players were important too. Blocking was great. Corey Grant was a wildcard. The passing offense was threatening enough that you could never commit the whole defense to containing Marshall and Mason, or Marshall might find Sammie Coates out there wide open. 2013 does not get recreated without a clone of Marshall and Mason, but I think it also does not get recreated without a clone of the roster.