Hi, I'm creespie and I have played league for about 3 years, I started playing jhin around 2 years ago and this champ is just an amazing and unique adc which I really enjoy playing and at least I suggest you all to try him

PASSIVE WISPERS

jhin's passive provides him a lot of movement speed later in the game, along with scaling ad but lowers his crit damage, which is not a big deal since the raw ad increase is way better. it also define jhin as a champion, giving him 4 shots, the 4th one is surely the most important, as it is a granted crit and deals more damage based on missing health. after the 4th shot you need to reload and aren't able to autoattack for 2.5 seconds, this could look like a big problem, but the passive also gives you a massive speed boost, which is insanely good to keep distances, kiting and having a good spacing with the enemies.

DANCING GRENADE

jhin'q consists in a bouncing granede that can bounce up to 4 enemies. If it kills a unit, the next bounce will do increased damage. this ability is really important to master to achieve a good wave clear and also a good poke, the best way to clear and poke at the same time is damaging the 3 mages of the wave so that the q will kill all of them, and then bounce to a enemy champion, dealing the max damage

DEADLY FLOURISH

jhin's w is a long snipe that roots enemy champions, if they have been damaged from an ally in the last 4 seconds and yu will get the speed boost granted from your passive. this ability can help team mates to achieve kills from a good distance, and is extremely good to setup ganks as well, combined with the traps that jhins place: when an enemy champion steps on a trap, jhin's w will root him even if they took no damage. sometimes it's a little ard to hit this ability, but the impact of a single root is massive.

CAPTIVE AUDIENCE

jhin's e consists in some traps he can place around the map and when a champion is killed by jhin, a trap will generate and activate instantly. the real importance or the traps is to give vision, to avoid ganks, to setup a wave clear on the backline allowing your q to oneshot the mages or to allow you to connect a w on an enemy champion to land a root. It's an important ability not to underestimate. also the slow that the traps applies to enemies is good to escape or kite easier.

CURTAIN CALL

the ultimate of jhin is a iconic snipe ability that allows you to shoot 4 bullets from a great distance, and the 4th shot work just like a passive one, always critting and dealing damage based on missing health. this ability is insanely good not just to get kills from a safe place, but also to steal objesctives: your 4th shots, in the late game, will deal greater damage than a smite and if the enemy doesn’t bodyblock it properly, you will be able to steal a drake, herald or baron with no problems. practice the side shots with this ability, and you will be able to get kills and objectives consistently

jhin's basic combo

consists in auto, q, auto, the best time to execute this is when you have 2 shots left, so that you can proc the crit and the speed boost and get away in a safe way.

the complete combo

is alternating autos with ability to maximize the damage output. so for example you will auto, q right after and move, auto again, w, auto, e or just move and auto. this will make you hit all the 2 abilites and the 4 autos for the max damage, you can adap the basic combo

the q bounce and w combo

needs you to time the q bounce on an enemy champion and your w, to hit the w as soon as the q hits, to have a free instant root on an unaware enemy

e into q

a basic wave clear combo consists in palcing a trap on the 3 mages of the wave and then using your q to kill all 3, in the early game using one or 2 autos to setup the q damage increase on kills is often a good idea

w into r combo

just an obvious combo, if you hit a w on a distant enemy you can ult right after to have a free hit on the champion and probably a free kill as well

I think crit is honestly the best option for jhin at the moment, so I'll talk just about that build, it's not really worth building anything else.

galeforce is the best mythic item for jhin, as it provides damage and mobility, using your 4th shot with the galeforce active will allow you to do a lot of kills on low health enemies.
collector is the best second option, as it gives an execute that works perfectly with 4th shot and galeforce combo, incresing your aggression potential even more, lethality is also good on low armor enemies such as mages or healers
infinity edge is the best item for raw damage, after you built at least 2 other crits item since earlier the crit damage boost will not apply. no reasons not to build it if you are even or ahead.
rapid firecannon is a solid option for jhin, as a 4th item or earlier if you are behind, the passive effect will give you the range to have an impact in fights and skirmishes even if you are behind and could be oneshotted if you walk too far. once again, works amazing with galeforce + 4th shot
lord dominiks is a solid item into high armor teams and you can build it as a second item instead of collector if that's the case. to achieve the highest damage, build it as 5th item.
guardian angel is a good option if there are too many assassins or the enemy team is just focussing you like mad and if you die the game is over. anyways, with a good spacing you shouldn't need it as you can still have an impact with w, ult and rapidfire cannon anyways.