"In my sleep!" Jacob laughs, although he doesn't make a move to jump yet, keeping his footing as best he can until the other man seems ready to jump. The shadows are still coming, the crevice is still growing, and the floor is still moving. Not idle conditions to fight in, and Jacob knows that they have to move.

So he bites the bullet and moves- left arm held up, pointing towards the beams across the gap and flexing his hand. The grappling hook fires, the sharpened metal digging into the solid wood and then the mechanism whirls, and Jacob jumps, letting the zipline carry him across.

It isn't qinggong, but Jacob wouldn't know where to begin with even saying that, never mind doing it.