Text and Idea: IntactAbid
Basically you can use an external that scans for a certain Float type Value which is basacally the maneuverability of your character's mesh, it then changes it to something unusable. (It can also be changed back on command, all this can be done by hotkey.) Your frozen mesh then Replicates to the server and basically while you can see yourself walking around and killing things, others will see you jumping and walking on the spot like a retard. This also affects NPCs. They will no longer to chase you since you are not within their peripheral vision while you'll still be able to hit them.