Venture into Killer Croc's lair and come out alive

Solve 40% of riddler challenges

String up one henchman and drop him to surprise a second (any play mode).

Solve 25% of riddler challenges

Face your biggest fears and keep your sanity

Solve 10% of riddler challenges

Survive the nightmare of the Scarecrow's fear gas

Solve 5% of riddler challenges

Escape from Intensive Treatment to the island surface

Rescue the guards and henchman from the Joker toxin in Decontamination

Complete a combo of 5 moves (any play mode)

Lose 100 games.

Defeat a Majini with a headshot while it's jumping.