A very simple mod, which will kill player whenever he reach a certain fall distance. Mainly designed to be used in CubicChunks servers with The End dimension with unlimited height, but can be used in vanilla servers as well.
Max fall distance is configurable.
@SubscribeEvent
public void onEvent(PlayerTickEvent event) {
EntityPlayer player = event.player;
if (player.world.isRemote)
return;
if(player.fallDistance > deadlyFallDistance)
player.onKillCommand();
}