Instructions
Smash the bricks in the slum with Killer Moth to build a fan. Ride up the current to the ledges and walk across them to get over the flaming garbage. Glide to the area near the police and assemble a tightrope. Joker will need to use this to cross over the flames.
Turn on the generator and then cross an awning to a dilapidated building to the right. Push the box over the edge and hold down the "Circle" button to build a bomb. Step on the handle to trigger the bomb. This will help out your goons as they battle the cops.
Move left and build a ladder to climb to a second generator. Turn it on and ride a lift up. Cross the bridge to the right. Switch your character to Joker.
Grab a railing on the right part of the next area. Switch to Killer Moth and have him stand on a button. This will lift the railing so Joker can reach the next area. Switch back to Joker.
Move Joker to the right to another generator. Turn it on to reveal some Lego bricks. Go to the bricks and hit the "Circle" button to build a helicopter. Fly this around and shoot its gun to smash objects in the area, including a gate to the next section.
Walk to the rear left section of the next area and pummel some bushes near the light pole. Assemble a jungle gym from these pieces with the "Circle" button. Use Killer Moth to climb to the top to reach a ledge. Move right across a bridge and glide to a tree. Kick down a ladder and push the garden gnome off the limb. Switch to Joker and hit the "Circle" button. Joker will turn the broken pieces of the gnome into a switch that will open the next gate.
Step on a panel in this area to transform Joker into a large mechanical Joker. Move to the right. Shoot the cops that chase after you and then stomp on the three trucks that appear. The mission is complete when these vehicles are defeated.