His reaction to the massive swathe of vines coming at him is to hold up the card he drew. Whatever it does, if it even does anything at all, will remain unknown. Steven's arm crashes into him too fast to even get in one final laugh or vicious dig, taking him straight to the wall and — perhaps unsurprisingly — right through it, straight out of the penthouse. There's no conveniently placed deck or pool out on this side of the building, so all that Childermass has to meet is wide open, completely empty space, all around.

While likely not the exit the magician had been hoping to make after his round of snooping around, it is, ultimately, a exit. There's no yell or scream or even the caw of a bird, he's just... gone, right along with a good chunk of that wall.