Minecraft wiki entry for Player_versus_Player, associated text: Made of about 3 layers of cobble, with creeper and witch farms (or just a lot of chests with these materials in them) and dispenser guns. Make sure to have about 10 brewing stands and people operating them, with about 20-30 beds and chests. Put splash potions of harming, poison, and weakness in the guns, hook up a redstone clock and watch the fireworks.