Master Yi is a fun LoL champion that offers two distinctive playing style, mid AP or ADC jungler. In this guide, I will focus on the AP side of Master Yi. AP Yi is a mid lane bully who does really well against a whole host of AP champions. There are only a handful of AP casters that I'm aware of can counter AP Yi well, there are Diana & Fizz.
AP Master Yi needs a strong CC based initiator in the team to help him shine during team fight. Despite AP YI dominance during laning phase, he will easily perish if the team does not have a good initiator as the game transitions into team fight phase. Initiators/Champions that work extremely well with AP Yi are Wukong, Malphite, Amumu, Garen (tank), Sona & Shen. Coincidentally, these initiators are also the type of champions you want use when going against AP Yi (OP healing ability). Your objective for playing AP Yi is to be the ultimate KSer (Kill Securer) in team fight with the help of your Highlander passive ability.
Primary Skill To Upgrade : Q (Alpha Strike ). Your bread and butter to harass your lane opponent and make him/her QQ. I prefer to finish this by level 9
Secondary Skill To Upgrade : W (Meditate) learn this after alpha strike to heal yourself when you are low in HP.
Tertiary skill : Q(Wuju Style). Ignore this skill until you have fully upgraded Q & W.
Ultimate : R (Highlander) Your initiating skill to chase and kill the enemy. Refresh all your abilities after each kill. Without highlander, you would not have your Quadrakill or Pentakill easily.
Summoner Spell : Flash & Ignite or Cleanse . Consider cleanse to replace ignite if you are going against enemy team with heavy CC heroes (Ie : Amumu, Sona, Twisted Fated & etc)
OR
AP Yi Pre Level 6 : Focus on farming creeps, harassing & zoning out your opponent with Alpha Strike. If your enemy is low in HP (<25%). You can flash in, alpha strike and ignite to get an easy kill. Play conservatively when you are up against AP casters that counter you (ie : Diana & Fizz).
AP Yi Post Level 6 : Again, focus on farming and harassing your lane opponent as much as you can. When your enemy AP caster is low in HP, it will deprive his/her ability to gank other lanes and also CS optimally. Try to purchase Deathfire Grasp as soon as possible because this item will give you a massive boost in AP damage.
AP Yi in teamfight : AP Yi should never be the one who initiates in team fight. You should be the last to go in and mob up the remaining enemies like a boss. Wait for your initiators and bruisers to initiate, wait patiently for the CC based enemy heroes to waste their CC skills on your bruisers, and then only you jump in with your Highlander (R), DFG & Alpha strike. If luck favours you and you get a kill off a low HP hero, your Alpha strike CD is refreshed and you get to Alpha Strike again and again until the your team gets an ace. Always remember to use your meditate when SHIT HITS THE FAN (Ie: not killing anyone with your alpha strike & you are getting surrounded). A single CC skill can disrupt your meditation and send your fragile AP Yi back to Noxus so you must use this skill wisely to avoid death.
Chasing low hp Ahri with highlander, and slain her with DFG, Alpha strike & Ignite combo
My favorite items for AP YI : Doran Ring (Early Game), Sorcerer Shoes, Deathfire Grasp, Rabadon DeathCap, Zhongya Hourglass & Void Staff (Sell Doran Ring). Get wards on the both sides of the bush after your first or second base to avoid jungle gank.
Alternative Items to consider
Vs Strong AP Team : Consider getting Abyssal Scepter instead of Zhongya Ring.
AP Yi Masteries :
Runes : 9 X Greater Mark Of Magic Penetration, Greater Seal of Mana regeneration, 9 x Greater Glyph of scaling cool down reduction, 3x Great Quint of magic damage
