Monster Mayhem: Build and Battle (Nintendo DS, Complete in Case, Tested) This listing is for Monster Mayhem: Build and Battle for the Nintendo DS. The game cartridge is in good condition and has been tested to ensure it works properly. It comes with the original case and cover art. In Monster Mayhem: Build and Battle, players can create, train, and customize their own monsters to defend their hometown from invading enemies. The game offers various environments to explore, along with customization options through battles, experiments, and tonics. Ships securely with tracking. Let me know if you have any questions!