I've seen on many servers that there a hole at spawn, you hop into it and you'll fall into PvP world. Can anyone tell me how to setup that? Also sorry for my English :]
You just teleport them once they hit some y level, usually void. It's actually a lot better to handle void damage, instead of listening to move event. I'm not sure what you're asking here. Do you need the code, plugin, advice, explanation or hand in the completed server?
I think he means that there's spawn at the sky and a pvp map at the bottom where players can jump down and pvp. So what you want to do is just do WorldGuard! https://poggit.pmmp.io/p/WorldGuard/1.1.91