"People pick a creature out of prerequisites that were not detailed, and I remember the characters running around a maze and they make those creatures fight when they run into each other.
I strictly remember a hisoka-style character named waterboy, and a large gundam thing getting slice and diced before getting it's head smashed. That's about all I remember."

I'm looking for a way to expand this. It was in a sort of maze. So you pick a creature, travel through the maze, and fought other people with their summons. But why? what's the goal, and what could be added to this to improve it's barebones, weak idea? I think something hunger-games style would work for that, but I don't think anyone wants to have their characters die, and they have to wait and make a new one.