The Doom Arena was first featured in the episode "The Birthday Boy". It's used as a type of torcher room for Lord Hater's and his minion's enjoyment.
The Doom Arena has many features to it. There is one big red button that activates all its weaponary and methods of torcher. It has a huge lazer cannon that looks somewhat like a bottle. Also it has one giant monster in captivity that can be trained like a dog.
"The Birthday Boy" - Its first appearance was in this episode. Peepers invited Wander and Sylvia for Lord Haters birthday. Hater was looking forward to see Wander cower before him. This didn't happen since Wander was more concerned about Lord Hater being happy on his birthday.