When you die by another Player there is a red message in the chat saying that you have been killed by... and for the player that killed you (the killer) there is a message saying you killed ...

if you die by a Player there is the red message + Lightning on the block you died but not doing any sort of Damages either to the blocks or to players.


Instructions:
Download the Plugin (pLightning)
put the plugin in your Plugins Folder
and Start your server.

I don't recommend using the /reload confirm, it can cause other plugins like ViaVersion to bug and not start.