Dr. Adams saving Batman's life by cutting open Dr. Cavendish's throat with a razor. It's horrific and disgusting, but it also breaks the cycle of insanity and allows Batman to conquer his demons.
After the Joker torments him with psychological games, Batman is left a shivering, terrified wreck. So what does he do? He plunges a shard of glass into his hand, using the pain to knock himself out of it.
Batman suffers a No-Holds-Barred Beatdown from Killer Croc and clambers onto the asylum's roof, where he finds the statue of St Michael smiting the Devil. The Bat then does some smiting of his own by impaling Croc with St Michael's spear. It's a perfect combination of symbolism and badassitude,