"Gotta go fast"
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Why this works
Jhin gets a movement speed boost whenever he Crits. So, if we build 100% Critical Strike Chance, we get a movement speed boost for ever auto we get off. In addition to this passive boost, this build gets a passive 15% ms from items, and the unique rage passive from your Triforce, which procs when you auto. So, at full build, you should see your movement speed reach at least 600 - 620 with every auto. Jhin can kite extremely hard with this surprising mobility, granted your getting your autos off. The only weakness this build seems to have is it lacks armor penetration, but that's not really a problem when you're doing 1k damage Crits anyways. Good Luck!