Mass Grave 1.0.2

First : find a place for your mass grave. go there in the game client, and type "client.printpos".
Now you have the coordinates.
load the plugin and it will create a config file.
Update the config file with the new values eg :
 

{
  "Mass Grave Position (you can use client.printpos ingame to get position)": {
    "x": -151.6,
    "y": 8.6,
    "z": -329.3
  }
}

Then reload the plugin with "o.reload MassGrave"

Now all player corpses on your server will be moved to the specific position. 

Note : This plugin pairs well with the "Persistent Corpses" plugin.