It's the sort of crude attack the Batman would normally be able to dodge easily enough, but with half his attention focused on keeping his balance in the slick mud, he can't quite move fast enough to get out of the way entirely. Killer Croc's shoulder and the side of his head slam into the Batman's abdomen, and the air whooshes out of Batman's lungs with an audible gasp. Batman topples forwards, his hands scrabbling onto Croc's back, finding purchase in the cloth of Croc's vest.