Chilloseum is an arena inside a cave. In order to get there, you need to go through the gates in ChillVille, cross the bridge and enter the cave, then you will find yourself in Chilloseum.
When activated, Chilloseum can get flooded by lava in order to stop victims from escaping.
Chilloseum was used by Su Tart in order to trap and attempt to kill Shamrokz and Albert. Su tart took advantage of the lava in order to stop people from escaping but tried to murder them using his own powers.
At some point, fictional Albert threw McChillington at Su Tart, taking him down and making them both drown to death in Chilloseum's lava (However, McChillington was somehow revived), ending Su-tart's tyranny once and for all.