Playing AP Yi relies on the very high AP ratio of Alpha Strike to harass and zone your opponent out of the lane. If you take too much damage, quickly return to tower, then use Meditate to heal. Once your opponent is gone, farm like crazy.

Once a significant gold and level differential has been built up, destroy your lane opponent.

AP Yi relies on the use of his ultimate Highlander to refresh the cooldowns on his Q (alpha strike). That being said, you need to maximize your single target nuking ability (which is poor).

Deathfire Grasp, Lich Bane, and Rabadon's Deathcap Allow you to nuke a single target and start your "Alpha Strike Avalanche". Rinse and Repeat, as needed.

Fiendish Codex helps your lane phase, by reducing cooldowns and improving mana regen, both of which are sorely needed. (Be sure to be nice to your jungler so he gives you Blue Buff.)

Master Yi Falls off Late game, so you need to make sure to have a significant advantage by then.

A great way to keep up the damage if enemies build magic resist late game. I recommend replacing Deathfire Grasp



This item is for early game; Along with the sorc boots, Haunting guise will cut through most magic resist, while also giving you some survivability. Replace Rylai's Crystal Scepter and don't buy the void staff until VERY late game (if needed).

While laning, never use q directly on a champion, unless you are trying to kill him, as that will make it easier for him to damage you back. Instead, use it on a minion and rely on the bounce to hit the enemy champion. However, it can be hard to tell if alpha strike will hit the enemy champion, but if you wait until there are only three minions left, and he is close to them, q onto a minion, and you will be sure to land the damage.

In a team fight, you need to stay back, until all the major disruptive CC has been used (stuns, suppresses, and any spells that displace champions, i.e. Draven's Stand Aside, as these will interrupt your Meditate. Once those are used, alpha strike into the fight, if you get focused, use meditate, and tank ALL the damage (trust me, unless you are ignited, you can take it). Focus the squishiest person, and pop your ult before they die.

Your combo:
Deathfire (45% of their current health (min 200 damage))
Alpha strike (300 Base + 500 AP damage)
Lich Bane Proc (110 AD + 500 AP)
Ignite
Auto Attacks

Once the Lich Bane Proc is available again:
Wuju Style + Auto attack + Lich Bane Proc (110 AD + 70 AD + 500 AP)
Ult
Auto attacks

Now that Person is most likely dead because they just took (before mitigation) 2100 damage plus ignite plus 45% of their starting health plus auto attacks.

If you shrink it down to one Lich Bane proc where you hit all your abilities at once, it's 45% of their health + 1480 Burst + 180 AD auto attacks + ignite. Yeah, they're dead.