In Minecraft 1.4, according to screenshots, there is a new kind of "buff" ability with beacons and diamond pyramids or something like that:
http://www.minecraftwiki.net/wiki/Beacon_Block Why not let challengers bring their own crafted "beacon block" to place in the pyramids around the fight arenas, choosing their extra buff? It could be like "types" in Pokemon - Dark, Psychic, Grass, etc... But instead it's Haste, Superjump, Resistance, Speed, or Strength. You bring your own "type" to the challenge.
Ideas? Or would it be too hard to construct?