Re: Best build for ember spirit?
Firstly, don't upgrade Mael to Mjol. You don't need the AS it provides. The extra ~2.5k gold could be spent elsewhere.
Secondly, don't build Blademail. Your role is not to tank damage. Your role is to be a pussy and SoF from far, while your teammates soak up the damage. Blademail is useless. Early mid game, your role is different. Your role might be to initiate. But at that stage, you probably wouldn't need Blademail. Janggo etc would be better. Mid-late game, you are NOT an initiator. Your Chains is a lousy disable that can be Manta'd, or they could just right click you in that 3 second duration.
Thirdly, Linkens is okay item, but not necessary. It does not add much to your early game, and is expensive. It is a situational item, that you get in response to what the opposing enemies are. Early mid game, there are many better choices to it. I'd rather use the Perseverance for Bloodstone (it's not a good choice either), or BF (great late game item for Xin).
Fourthly, early on Xin is played as a ganker. His main sources of killing damage are from his skill set. Past that stage, his skill set isn't enough to kill. That's where SoF comes in. You need to boost it up. This is done with more +Damage. Late game, you are mainly spamming it. As such, you do not need any attack speed items. Raw damage is preferred. Thus Crys/Buriza is a fantastic choice. Mael synergises very well with SoF, because lightning is proc very often. Hence, Mael is often gotten as your first damage item after your basic items (usually Janggo Bottle Boots). After that, you generally want more damage items. MKB is alright, but for it's price and build up, I'd rather get a BF. Then you get more and more BF. Whether or not you should get BF first or Crys first depends on the game.
Fifthly, you should consider situational items. Manta is useful against Silence, as with MKB. Most Orbs are useless, because you should get Mael over any of them. Skadi could be considered depending on your needs, because 30% slow to everyone every 6 seconds is quite ridiculous. BKB is obviously helpful.