"Oh, I see how we're playing this," Bucky observes.

Steve shakes his head. "Better you than me, pal."

"Well," Bucky says, as he starts pulling a block very slowly from a lower level, "some things are worth the risk."

He manages to get the block out, then makes himself still the way he would if he were sighting a target. After a long moment of perfect immobility, he stacks the block on the now-growing single-width stack and lifts his hand in the same motion.

The tower sways, but remains intact.