Hi I'm Rionel. I started playing Xin from season 6 became of his easy kit and great potential. People often ignore his great ult and passive healing that scales with both AD and AP!!! His kit is quite deceiving as it seems like he is a good jungler, but in reality he is a way better laner(specially TOP). Being a jungler you are forced to max E first or second(WHICH SCALES WITH AP!!!) but being a laner you can max W first and Q second(both scales with AD).
he got good sustain and poke and with just enough movement speed, he can escape situations without a lot of problem. This guide is still in progress so I'll update it frequesntly. And don't forget to upvote my build if it helps you as it will help me in return also. And don't forget to share with your league buddies if you find it interesting ^_^ ~peace~

Take scaling magic resist because at level 1 mages are not that offensive as they have only one ability and almost all mages are more or less completely dependent on their abilities. And the other reason for taking it will be that you will not be building a lot of magic resist items(only the maw) in my opinion as it will take the item storage which could be used to get a better item.

Plain armor seals because "duh".

Attack damage marks to empower your autos and Q and W.

Attack speed quintessence so that you can finish your poking combo E-Q-W faster and retreat faster before the opponent laner can do their combo.