This Yi build depends heavily on AAs, Q should be used to dodge CC and never to engage if the enemy which could be around or you are attacking still has their cc spell up. The main Idea of this started, when I looked at Eclipse and thought, why doesn't anyone build this Item? 6% Max health physical damage per hit is insane in combination with attack speed and thus you need those boots. BORTK also grants attack speed and life steal on top of Eclipses omnivamp, but the current health damage of 10% in combination with Eclipses max health damage seemed like a fun combination. BT is the third core Iteam. I thought about attack speed items for this build, but realized soon, most are crit items, so I looked at all of them and BT stuck out, with 20% Life steal and 55 AD, eventhough it doesn't grant attack speed, alacrity, BORTK and boots should be enough. (That's what I thought) In reality you want to stack as much atk speed as possible in order to procc Eclipse's effect as often as possible. You really need Berserkers and Blade and on top of that You may build Wit's end and then go with tank Iteams or go Rageblade and go crit and atk speed iteams.