Unlock the Arkham Aryksylum, and to the left of you, there should be a staircase. Go up it then go inside the second cell up there. Then destroy the bed and you should see a button that your supposed to build. Build it, then step on it and on of those fat cylinders will pop out. Build it, then there will be two handles on the wall (Your supposed to use clayface or any other super strong guy. ) Hit A and hold. Then go through the hole into a room destroy every single possible thing to destroy to give you a headstart. In the middle of the floor there will be 4 buttons. Step on the buttons quickly so their all green. After that there will be a whole BUNCH of fat cylinders loaded with thousands of dollars. ( Mostly blue studs. ).
To unlock this mode, beat the villan side story. Go to mini games and look for the last game. To play, you have time, and you play as a bunch of people, and look for the villan they tell you.