This is my newest map. Note that the chickens can escape. Also note that you have to fly into the arena when you spawn. Basically, you survive while doors open and dispensers do things (Spawn mobs, shoot arrows, drop things like bows and eventually diamond stuff). The doors and dispensers are hooked up to a clock and make the map work.
Link below \/ \/ \/ \/
https://web.archive.org/web/2020/http://www.minecraftworldmap.com/worlds/MUkoZ
Link below \/ \/ \/ \/
https://web.archive.org/web/2020/http://www.minecraftworldmap.com/worlds/MUkoZ