It's actually quite easy to win vs. a Jhin as Twitch. If you abuse your invisibility to gap close and hard engage, he counters Jhin for the same reasons Vayne wins at level 6. Just overwhelms him with burst damage that Jhin can't respond with fast enough.

Jhin can win the matchup if he pokes hard enough during the lane phase and actually uses his early pressure to his advantage, but most don't do this.

This is a great question!

A lot of twitch players conflict with the domination / sorcery setup, but I'll tell you what I've figured out from my personal experimenting, and other high elo twitch players.

Taking Domination: If you want to run with the domination tree, you should only consider taking it if you are playing Twitch jungle, not twitch ADC. Even on jungle, domination is not always your most optimal rune choice. Ideally, you want to take domination on twitch jungle if you are planning to play the early game especially aggressive, and synergizes very well with Press the Attack. Generally if you do choose to take domination, you would take Sudden Impact no matter what, and then you can choose between Eyeball Collection, Ravenous Hunter, or Ultimate Hunter. These individual choices all come down to your personal preference, and what you believe will be most effective into certain team compositions.

TLDR: Take Domination for an aggressive early game on Twitch Jungle, but don’t ever take it on Twitch ADC. You can snowball easier with this build, but won’t scale as hard into the late game.

Taking Sorcery: Sorcery tree should always be taken secondary when playing Twitch ADC. While Twitch can win lane, you’re not often utilizing the runes from the domination tree in the laning phase, especially Sudden Impact. This is why we take Sorcery instead! With this tree, our main objective is to play to farm in the laning phase, then scale up later on. If we get fed, then that’s even better! There are two possible rune setups for Twitch with Sorcery secondary. The most common, and generally the most effective is Absolute Focus and Gathering Storm. There is a less common, but still viable second option available. This entails running Celerity, and Nimbus Cloak. The reason for taking these, is to let you kite much quicker in the moments that matter the most! Whenever you unstealth and Spray and Pray as Twitch, everyone is either going to be 1: Running away, or 2: Chasing you down. So for this reason, taking nimbus cloak and celerity can be more beneficial versus enemy team compositions that can quickly run you down. For example: champions such as Xin Zhao, or Jax that you need to get away from as quick as possible. While this setup is definitely viable, I don’t recommend using it unless you are very experienced on Twitch. If you want to focus on learning Twitch, I highly suggest just running with the standard setup I’ve provided. While the other setups can be utilized, it’s best to stay in tune with a cookie-cutter build and rune path until you feel like you’ve really mastered his gameplay.

TLDR: Take Sorcery on Twitch ADC every game in order to scale up as best as possible, and deal the maximum amount of damage when it matters most (Late Game)! This is especially the best on ADC Twitch because you won’t usually want to play super aggressive / bursty during the early game, and instead just focus on playing safe and farming.

I hope this thoroughly answered your question and helped sort out any confusions you may have had. If you have any more questions, pop in my stream or let me know here! Best of luck on the rift with the rat!