I help run a modded FTB Direwolf20 1.10.2 server. I'd like to give players a short duration of immunity after logging in, e.g. 20 seconds, to make up for the lag/logging in time which often results in deaths before the player actually logs in.

How do I do this? Adding a new mod is okay, but I'd prefer a vanilla solution if possible. I have FTP and multicraft access to the server (not root access).

Thank you!