This was my dream last night:
Apparently I did what I needed to do, because it flashed forward to the second part, which was entirely nautically based. The Joker was terrifying people on the beaches along the coast, because he had gained Aquaman-like powers. I/Batman managed to catch him at one point by firing a grappling line horizontally, hitting a big pier, and pulling myself through the water at high speed, grabbing him on the way by. The Joker wasn't too put out by this, though, because somehow he lassoed me when I got on the pier so I couldn't get away. I was above him, but he was climbing up towards me and it was clear he could easily overpower me, but that wasn't his plan.
His plan turned out to be, there was a cruise ship right by the pier with a bunch of people with high powered rifles. When I thought it couldn't get any worse, it turned out he had planned the whole thing so that a giant submarine breached and smashed up the pier and the cruise ship. The waves/tide pushed everybody into a canal, which was lined with more dudes with high powered rifles. I remember calculating that there was like a one percent chance that someone could swim by those riflemen without getting shot at such close range, and sure enough I did get shot twice, because I wasn't batman any more, just Bryan.
But I did survive to advance to part 3 of the dream, where people started getting washed up in this Mad Max-type setting, except it was on the beach. All of a sudden this dervish of light and evil started charging around the beach looking for stuff to kill. I tried to hide behind some old tires in the garage, but the dervish found me. Turns out it was the spirit of the Joker, and he was unkillable and all powerful. He rode me around and extended his tendrils trying to latch on to humans, from whom he could draw power to reincarnate stuff. He did that for a while and it looked like it would be really bad.
Luckily, somehow we ended up on an elevator. As the elevator rose, it revealed a cat and Russell, the bassett hound. the cat turned into Batman and Russell turned into Superman. Superman flew out, grabbed the Joker, snapped his neck, and threw him to the bottom of a pool, so that the real Aquaman could handle him.
Your move, Mr. Nolan.
Luckily, somehow we ended up on an elevator. As the elevator rose, it revealed a cat and Russell, the bassett hound. the cat turned into Batman and Russell turned into Superman. Superman flew out, grabbed the Joker, snapped his neck, and threw him to the bottom of a pool, so that the real Aquaman could handle him.
Your move, Mr. Nolan.