Okay.I know how to be invincible without the extra on.
Supplies needed:free play,gun character(person with gun),& a place with that toxic waste(ex:VERY FIRST LEVEL)
Steps: 1-switch to the gun character. 2-go in the toxic waste,then press shoot as rapidly as you can while holding "move" in any direction until you get out of the toxic waste. 3-go near an enemy.Let him/her hit you a couple of times.I hoped you liked it!!!!!=)
These two characters are unlocked when you beat the game with the corresponding task completed.
Unlock Hush: Rescue ALL 25 civilians in the game. To find out which levels you still need to rescue a civilian look for the small face with either a happy or sad face indicating whether or not you still need to rescue them.
Unlock Ras Al Ghul: This villain whose name means 'The Demon's Head' is unlocked when you have collected ALL 300 of the mini kits. There are 10 in each of the 30 levels.
To unlock Arkham (psychiatric hospital for the criminally insane) you must achieve 'True Villain' status on ALL levels in the Villain storyline by collecting enough studs to max out your stud counter on each level. To access the villains and the level go to the right of the Batcomputer and down the ramp and pull the lever. Then go through the door on the right to reach the Memorabilia room where you then climb the ladder at the top.
To unlock Wayne Manor you must achieve 'Super-Hero' status on each of the Hero missions or alternatively achieve 'Super-Villain' status on each Villain mission. To reach these statuses you have to collect enough studs to max out your stud counter on each level. To access the mission go to where the vehicles are in the Batcave and then go to the far right and down to the bottom. Step on the elevator which will take you to the Memorabilia room and the Wayne Manor mission is in the upper left corner.