Fou-Lu has flight in his dragon forms. Boxes on the ground are no impediment to him.
Fou-Lu in a berserker rage is no way gonna have enough wherewithal to think 'I gotta fly over these boxes'. He's gonna bull rush and try to kill things with his sword. And then he's gonna go boom since those boxes explode when tipped over
She's perfectly capable of run-and-gun. If the cheese is vital to victory, she needs to eliminate anyone and everyone on the other team who might attempt to prevent her from securing the cheese.
No doubt she can shoot as she's running for it. Which'll wind up plowing her right into Big Boss + Master Chief, and then she's kibble. Especially if she's paying attention to the dancing naked guy/girl up there, as indicated above
Duke's got a jetpack. Also, he's a gunner. He doesn't have to traverse anything.
Duke raging with the power of Saxton Hale is not gonna go 'Man, I need to fire up my jetpack and FLY over there'. He, too, is gonna charge. And get blown up
Bryan has his gatling gun, so he doesn't have to go tripping into the world of boxes if he doesn't want to; he also has his inhuman durability (no-selling tank fire and masses of machine gun fire), so a single box hit won't kill him.
And Bryan's a homicidal loon, so assuming he'd gain some magic tactical genius is kind of silly. Besides, no one on your team actually knows those cardboard boxes are anything but cardboard boxes. They won't, until they've started knocking them over and getting exploded
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We are thought, and reality, and concept, and the unimaginable