Chapter 4: Asylum Assignment
Start by destroying the lego pieces near the elevator and reassemble them to get Robin's Hazard Suit. Use it to take out the fire. Head to the right and dive to the water. Activate the panel to the left to unlock Batman's Electricity Suit.
Use Batman to pass through the electical catwalk then drain the power from the generator and clear the underwater path for Robin. Switch to Robin and continue to the right. Destroy the debris for the blocks to float and create a footbridge for Batman.
As Batman, continue to the right then drain the generator's power again. Switch to Robin then destroy the fan blades to enter the tunnel. Head to the left first to find a mini-kit.
Continue to the right and destroy the second fan then activate the terminal. Switch back to Batman and power up the generator to open the underwater gate for Robin. Go past the gate and have Robin destroy the green machine to clear a path for Batman. Have Batman power on the generator again to open the floor panel inside the cage. Switch to Robin and float up to the opened floor panel to get inside the cage. A mini-kit is located to the far left.
Continue to the right and have Batman destroy the desk then reassemble it to become a paddle switch. Push it for Robin to continue forth. Continue to the right and let Robin return to the surface. Now aim for the blue circular switch then press B to shoot a stream of water to it. This will activate the stairway.
Continue upstairs and power on the switch to freeze the waterfall. Climb up then defeat all goons. Destroy the shining blocks in the upper right portion of the floor and reassemble it to get Robin's Ice Suit. Destroy the two valves to create a fountain. Freeze them and the waterfall in the middle to gain access to the upper floor.
Make your way to the other side and past the freeze jet then use the paddle switch to power off the jet and create a safe passage for Batman. Continue forth and defeat the goons. Have Batman power off the generator in the upper left then control Robin and cross the frozen wall. Continue to the right and a hatch will open. Jump down then pull the lever.
Use the paddle switch to turn off the freeze jets. Have Robin shoot the waterfall with his ice cannon to freeze again then make Batman reach the other side to access the electrified terminal. (You can ignore the mini-kit during your first time in this stage) Power it off then step on the two buttons to continue.
In the next area, head to the right and defeat the minions. Switch to Robin's Acrobat Suit and swing on the handle bars to reach a mini-kit.
Power up the switch to the left of the giant monitors then use Robin's Acrobat Suit's gyro ball ability to control the conveyor belts. After completing the simple path, the box will appear. Use your grappling hook to pull the box open. Defeat the enemies that will appear as well.
Reconstruct it then change to Batman's Sensor Suit. Go on stealth mode and go past the security cameras. Deactivate them using the nearby switch, then change to Robin's Hazard Suit to put out the fire. Change to Robin's Ice Suit before moving on. Continue forth then examine the green wall and fix the alignment of the conduits inside.
Cross the bridge then freeze the waterfall to access the terminal. Activate it to create another bridge. Move along to reach the large door. Defeat all the enemies then scan the blue wall. First, release the batter in the top left corner then operate the mechanisms until the battery reaches to the lower right. This opens the large security door and stairs.
Continue along the main corridor where more prisoners will break free and attack you. Defeat them until you reach the some toxic sprays. Pull down the lever to the left and activate the terminal to the right to get past them. Meet up with the Scarecrow to start the boss battle for this stage.
Have Batman go on stealth mode and just defeat the prisoners and attack Scarecrow until he's down to 3 hearts. You should see some bouncing lego pieces from both sides. Reassemble them to become valves. Activate the valve and have one of your characters hang on the bar. Activate the valve again to retract it so the hanging character can jump on the ledge and activate the terminal there. Do this for both sides and you should be able to attack the Scarecrow normally until he's defeated. The stage is completed after his defeat.
You can now activate remote bat terminals which will allow you to fast travel to major known locations, reveal villain locations and select the vehicles you want to ride as well. Activating some bat terminals reveal the location of villains. Defeating them will allow you to buy them so you can switch to them and use their skills whenever needed.
Remote terminals are marked by red beams in the sky. For tips on how to find and collect these character tokens, please refer to this guide's Character Tokens section.