Lane harass and utility damage.
Empowered abilities and resource manipulation
Hitting a champion with spells hurls a comet that deals adaptive damage at them. Landing more spells reduces Arcane Comet's cooldown.
Periodically your next ability used has its mana or energy cost refunded and restores some of your missing mana or energy.
Gain 3% extra MS. Gain extra AP or AD, based on your bonus MS, Adaptive.
Your first ability hit every 20s burns champions.
9% attack speed, 10 ability power or 6 attack damage
Takedowns restore health and grant bonus gold.
Deal more damage to champion with more maximum health than you.
Arcane Comet is a solid offensive rune choice for Jhin thanks to its high Bonus AD scaling. If procced when using [W] for a root or [R], it's almost guaranteed to hit.
Manaflow Band provides you the mana sustain so you can start Doran's Blade instead of the typical Doran's Ring.
As an alternative, you can also start Doran's ring and talk The Ultimate Hat here instead.
Jhin is one of the fastest moving AD Carries in the game thanks to his passive, Zeal stacking, and tendency to build Ghostblade allowing you to position better for your 4th shot.
The Movement Speed from Ghostblade and Zeal items act as a small AD steroid thanks to Celerity.
Scorch is an all-around solid lane harass rune. You should be able to proc it relatively easily with [Q] or [W].
Gathering Storm is a decent alternative for late game damage insurance.
As a long range utility AD Carry, Jhin is often licking up a number of assists throughout the game and the extra bit of gold and healing can go a long way in snowballing a lead.
Cut Down is an AD Carry's most reliable form of damage mitigation, especially when dealing damage to the enemy top, jungle, or mid who often build at least 1 health item.