Slayers (and Buffy) can take a beating and are somewhat resistant to damage, but are in no way impervious. They can be stabbed, shot, get sick ,etc- just like normal people, but they recover and heal much faster. Its not instantaneous, but they can. I would say that Buffy belongs more in the supers category than humans because she is kinda like the female Captain America. Only difference is the shield. Joker isnt fighting Cap and his shield though. He is fighting Buffy and she has nothing that can stop acid melting her face off or something that renders her immune to the Joker Gas. Nothing. Show me where she took a shot of acid to the face and kept fighting. You cant. I can, however show you times she was knocked the hell out and\or died. She may recover from alot, but it takes her a few hours\a day to get back on her feet. Joker just has to keep her down for the count this round and is very capable of doing so. Buffy has been knocked out a few times with blows to the head. So its quite possible that Joker whomps her with the mallet and she goes night-night. She may be strong and have great durability, but she isnt invincible. She can be knocked out- even by electricity. Remember when Dru zapped her with the cattle prod? I do, Buffy took a nap. By the rules of this tournament you can lose by death or knockout. It is very possible for Joker to knock her out and likely that he would\could kill her. Slayers are tough, but Joker has this one. Buffy is not the invincible chick that people are trying to make her out to be. Joker, on the other hand, is exactly sick, twisted and more than capable of taking her out with what he has up his sleeve.