I made this map this using singleplayercommands/worldedit and used JohnSmith texture pack/resourcepack so use JohnSmith otherwise it will look terrible! Basically I have terraformed a few mountains and caves, you start in a nice little valley amongst the ruins of a dead civilisation which met its tragic end due to the mobs that inhabited the caves. This project was intended to be a server map, you can download it (Download out now!) I recommend getting some plugins like that one that fills chests as all the 10 hidden chests in the map are empty, also a round plugin so that the chests refill each round, some anti-grief plugin so player can't destroy or mine their way out. So basically you can put this on your server, edit it to your taste and let players on your server have fun on this mob survival challenge!
Remember if you do put this on your server give me credit and do not attempt to claim it as your own!

Additional Notes

P.S
This is intended for servers with plugins so playing this without any plugins won't really work as the chests will not refill but you could just switch to creative and give yourself some gear then switch back, put it on hard difficulty set it to night and fight the mos by yourself. But it is recommended to use this on a server so you can get some nice plugins with rounds of mobs and stuff!