I am wondering in which language file the announcement "In Deathmatch, it's a free for all, the goal is to kill as many players as possible!" can be found.
I look into EventManager.json and EMInterface.json. It's not there.
I would like to change/add something.
Thank you.

It should be in the language (lang/en) files for EventManager. (If you are after english)

But it is not.

No, the message will be in the file for the Arena Deathmatch plugin, in the lang/en folder.