The Coliseum

"Then we'll settle this in the Coliseum!"
 * - Grasshop

The Coliseum, or Coliseum for short, is a form of technology designed and used by the Invectids. They are small spheroid devices that transform into a large arena, for the purposes of battle.

History
Prior to the arrival of Hunter Steele into the Inner World. The people of Arachna reached an accord with the Invectid Nation. So as to avoid another all out war, whenever a Spider Rider and Invectid came at an impasse during a dispute. There would be a duel in the coliseum, who so ever won the duel won the dispute. After the duel the losing party would be expected to retreat from the area, if they were allowed to live.

Physical Description
The coliseum is an entirely free-standing structure. Unlike a colosseum from the Surface World, it is elliptical in plan and is over fifty feet wide and about a hundred feet tall. The central arena is a wide circle, surrounded by six pillars which rise above and curve inward to form an energy bubble around the entire arena.