Not looking for one to kill mobs, looking for one that just blocks them from going through, but allows players access to pass through, is that possible?
Unfortunately, Bukkit API does not provide ways for plugins to control mobs' AI. This plugin would require messing with NMS or CraftBukkit code, meaning that the plugin will not work with some other server implementations. Or there are a couple workarounds: A plugin scan the world once every second and can keep track of all mobs and their last known location. If any mob enters a restricted area it'll be teleported to their last known location. Place transparent blocks like glass panes where the forcefield should be and server can send "fake" air blocks instead whenever client loads that chunk. Then when a player approaches that block, they'll be teleported in the middle of it so that the server isn't going to think that it the client is hacking with noclip. The blocks should be transparent so that players don't suffocate in them. Moving through the forcefield will cause a noticeable delay for players who experience network lag.
why would it not be just a glass pane? can you point me to a world where this is working? so I can see it?
