Hello,
My name is Kayotic. I like to call myself a Jhin main, but I know I'm far from it. I got to Pathfinder (level 5) with Jhin in only 3 days of playing him with multiple flawless games (using the build Im sharing) in my time playing. Recently I have been using a build from this website (forgot the name of the creator but if I find it I will credit him/her). However I knew about how Jhin's movement speed was increased greatly when he crits. So in an attempt to exploit this system, I made myself a build that gives Jhin 100% Crit chance, so you will never feel slow anymore. (Jhin is one of if not the slowest moving champion in LoL)

Be sure to make use of your Q ability; Dancing Grenade, as it makes for very easy farm and CS. Also, it has a very short cool down time, of only 5 seconds. Use the "Final Shot" method. When you are on your guaranteed crit shot, (the most OP thing in the game) try to use it to poke down the enemy AD Carry or Support. If there is a Blitz, Thresh, etc support, move in awkward ways making sure to not make a pattern so you don't get pulled because getting out of a pull is not easy.

Pros:
-High Damage
-Crits make you move faster
-Can Root enemies for easy ganking
-Insane Ultimate
-Great Range
-Great Farming ability
-Abilities are great for poke
Cons:
-VERY squishy
-Slow moving, unless you hit a crit
-Very difficult to master
-If you get pulled by Blitz, Thresh, etc, expect death