The Joker was operating inside Batman’s and Harvey Dent’s (and pretty much everybody else’s) OODA loops. He was changing the situation and exploiting it before his opponents could comprehend. Textbook case.
As Boyd observed in Patterns of Conflict, chart 132, if you can operate inside your opponents’ OODA loops, you can do all sorts of neat things, including:
Generate uncertainty, confusion, disorder, panic, chaos … to shatter cohesion, produce paralysis and bring about collapse.
Should seem familiar to Batman, Dent, etc.