Diablo has the "hot-headed" trait. This means that he will occasionally overpower his attacks. This works just as if you scaled up the power of an attack, making them stronger but requiring more energy, and you have no control over it. However, if he tries to overpower an attack to the point where it takes more energy then you currently have, he will end up being stunned. Watch when you use his Hellfire, and stop him if he is going to overpower it.
Hovering objects
Choose an object that you can pick up. Pick it up stand in an open location. Right click on the object you are holding and select "Throw". You will see your character start to throw it, but the object will stay hovering above you. You can move away from it and it will still hover. Note: This does not work on cars.
Mr. Mechanical's giant robot
If you get up to defeat Mr. Mechanical's giant robot, you can create a character with 10,000 or more prestige points.
Multiple canister use
Surround a canister with all your characters when one is found. Press [Space] to pause game play. Click on the "Use Canister" command on all your characters. When game play is resumed, every character will be able to use the canister.