Minecraft wiki entry for Creating_a_challenge_map, associated text: Create a superflat world and make a 400*800 barrier cage. Have the map on Hardcore mode. Add spawners for monsters that don't naturally spawn, such as vindicators, cave spiders, drowned, and a command block to summon a wither. At evening, bring in the contestants. Clear everyone's inventory and give each person a diamond sword, a full set of iron armor, and a bow enchanted with Power II and Infinity. Give everyone an arrow and a shield. Don't forget to give everyone some blocks. When the competition starts the wither should be summoned. Have everyone fight the monsters. Whoever is alive the next day gets a prize and can keep the wither's nether star and mob drops.