You can either follow these rules I made up or make up your own:

1. Don't play on PEACEFUL.
2. If you are using this map on a server, turn pvp on.
3. You can only break stone/cobble/anything related to stone with a pickaxe.
4. Once a player is dead, He is kicked out of the Arena until the next round or so.
5. No Flying
6. When a player is dead, he can play on peaceful and watch the rest of the fight.
7. People at the top of the Arena(The place with goldblocks and ironblocks) can fill up mine carts with stuff and send resources to the survivors below.
8. People at the top of the Arena get to light activate the TNT to send a warning or something (the Tnt doesn't ever hit the ground)
9. Stay inside the Arena.
10.THERE IS ONLY ONE WINNER