- Not to be confused with the other battle arena.
|"While we're stuck waiting, why don't you tell us who's really under there?"
The battle arena is a fighting arena in Terra Domina.
After Lloyd, Nya, and Jay are able to make it to the top, they enter the battle arena and are forced to choose their best player to fight. The remaining ninja choose Lloyd and he is paired up with Avatar Harumi.
Lloyd thinks she is real, but Jay and Nya know she's just an NPC. However, Lloyd cannot hear this and is struck by Avatar Harumi. Lloyd contemplates whether to fight her or not and ends up doing so after realizing she's not real.
In the end, both players strike each other at the same time with Avatar Harumi being defeated and obtaining the final Key-Tana; however, it comes at a price as Lloyd loses his remaining life and gets cubed. Then Jay and Nya collect the Key-Tana and continue on.
The battle arena can be seen behind Jay and Nya while they were getting pass a conveyor belt with rotating shurikens moving in a certain pattern. Then the battle arena is seen again when a shock wave travels throughout Prime Empire.
- The battle arena's structure is similar to the structure of the Temple of Madness.