You can knock out enemies with Batarangs. I believe you can only do it on a single enemy at a time though. Get the auto-aim symbol, throw three in rapid succession. The third Batarang glows red and knocks the enemy out for the count. I just didn't like the Mad Hatter part. Just kind of jumps clean out of left field and disappears right back into irrelevancy. A bit trippy, but it fails to deliver the same rabbit-hole experience you got with Scarecrow in Asylum or with Ra's in City.