First off download the server pack. When done extract the files to a separate folder. After first launch, Open eula.txt and accept it by changing false to true.
>SERVERFOLDER/server.properties.txt
Lower "view-distance=10" (Recommended 4-6)
>SERVERFOLDER/config/Fishs_undead_rising.cfg
I:"raven spawn rate"=8 (Recommended 2-4)
I:"piranha spawn rate"=20 (Recommended 2-4)
>SERVERFOLDER/config/sponge/global.conf
keep-spawn-loaded=true (Change to false)
spawn-limit-monster=70 (Recommended 25-30)
>SERVERFOLDER/config/sponge/worlds/DIMENSION-NAME/DIMENSION-NUMBER/world.cfg
To stop every dimension loading when the server starts up, you have too manually edit each of the dimensions world.cfg file, It should look like this:
sponge {
world {
# If 'true', this world will load on startup.
load-on-startup=false
}
}
Type /worldborder set 10000 (This sets a -5000 , -5000 x 5000 , 5000 block worldborder around X-0 Y-0 Z-0)
You can change the size of the worldborder after you pregen.
Then type /pregen gen startWorldBorder (This will pregen everything within the world border you set)