Update: Added Xypherous discussing the kit rework an several more red posts!

Turns out Master Yi is the going to be the next champion to receive both a visual upgrade and a kit rework!

Continue reading for more details!

Here is Morello with the scoop:
"Master Yi's slated for a visual upgrade and kit rework in a coming patch. In addition to a new model, more polished animations and expanded voice over, each of Yi's abilities are getting updates to address issues with his popular AP and AD builds. His kit should still feel familiar to both AP and AD enthusiasts, and we're hoping to retain most of the fun aspects of both playstyles.

We had three basic goals with the Master Yi updates:
Polish up Master Yi's art and aesthetics so they hit the same level of polish as new champions
Merge the most enjoyable aspects of AP and AD Yi into a single cohesive playstyle
Place more emphasis on mastering Yi's abilities so he's less frustrating in lower level play and scales better with player skill

Why'd Master Yi get a new look?
Master Yi was one of the first League of Legends champions ever created. Back then the game had a less established artistic identity. We've learned a lot over the years, but we also thought it was important to preserve his core look and feel as a part of LoL history. The differences are subtle, but when you check out the new Yi you'll notice his proportions are more in line with his fellow champs, his animations are more polished and he has some sweet new acrobatic moves on Alpha Strike, Double Strike and Highlander.

Why does Yi need a design update?
Most of AD Yi's power comes from his basic attack combined with the steroid effects on Wuju Style, Highlander and Double Strike. Without AP, there's almost no incentive to master your active skills – Meditate's not a very effective disengage and Alpha Strike can actually make you lose DPS since you could be attacking during the cast animation. By contrast, AP Yi requires careful management of Alpha Strike, Meditate and Wuju Style to maximize damage and survivability, but doesn't do a whole lot with his basic attack until he gets Lich Bane.
While both these playstyles are interesting in their own right, they don't necessarily have to be mutually exclusive, and there's probably a unified design that offers the best of both. Moreover, while AP Yi's a rather compelling late game fighter, he's extremely frustrating to face in lane, so scaling back Alpha Strike and Meditate was a necessary part of the update.

What's happening to AP Yi?
While straight AP probably won't remain a prominent build, AP Yi players will find many of the familiar elements of their playstyle intact. While Alpha Strike and Meditate are scaled back so they're less overwhelming in lane, carefully managing your active abilities will play an important role in staying alive and maximizing your DPS. You'll also have the added power of AD Yi's basic attack to make up for your less devastating Alpha Strikes.

How's the new Master Yi play?
We imagine the updated Master Yi will work well in both mid lane and the jungle. We definitely want to skew his itemization away from the typical tank-heavy fighter builds. The updated kit rewards glass cannon DPS builds that rely on disengaging with Alpha Strike and Meditate to stay alive. Most of his power still comes though items rather than natural scaling through levels. Overall, Master Yi players should have more strategic options, and more incentive to master his full kit to fight effectively."

Here is Xypherous chatting about the finer points of Master Yi's reworked kit.
"I can answer a couple things about the kit in the... 15 or so minutes I have here - sorry there isn't much. Solcrushed, who is handling a lot of the tight-end balance will be around in the afternoon, I think. Quote:
Playstyle and Kit Overall, none of his targetting paradigms have changed - nor have any of the abilities changed in their use case. The majority of this was scaling, timing, cleanup and a couple minor retouches. Quote:
Alpha Strike For example, Alpha Strike now scales off total Attack Damage, deals physical damage and has some light interactions with critical strike and attack speed. Hitting an enemy will reduce the cooldown of Alpha Strike - while critical strike will add mini-crits to the skill based on your critical strike chance and damage. Alpha Strike will have fixed travel time between bounces - so an Alpha Strike on 4 targets will give you a consistent time of untargetability, rather than being proximity based. This also means that your opponents will have a better sense of when you'll fade back in, so good luck on that. Alpha Strike has lost its AP ratio... for now. We're experimenting with some models here under-the-hood for a pure AP playstyle - unsure how it'll fully pan out.
Alpha Strike now counts as movement for the purposes of items such as Statik Shiv. Quote:
Meditate Meditate has changed from a flat armor / magic resistance boost to a % DR model as penetration was causing really weird damage potentials against what is supposed to be one of Yi's primary defense mechanisms. It also restores more health the lower health you have - meditating at lower health will provide a bigger damage buffer / health restore in general than meditating at high health. Quote:
Wuju Style Wuju Style has been changed from a flat boost to a % boost in total attack damage. This smooths out his power curve a bit better based on how well he's doing throughout the game, rather than spiking early at around level 9 and then really needing to snowball off a couple kills to remain decent. Wuju's style's active now deals true damage based on a % of his total attack damage - Master Yi needs to be a threat, regardless of who he's attacking - but the damage difference between destroying squishy targets and piercing high armor targets was getting a bit absurd. In general, Wuju Style will add less attack damage early but more and more as he builds additional Attack Damage and ranking it. We've compensated some of this early damage loss with an increase in base statistics and survivability. Quote:
Highlander One of the things we noticed from continuous playtests was that the more you made Yi focus on Alpha Strike and Highlander gameplay - the more of a restriction Highlander became. One of the primary skills a player needs to know while playing Yi is when to engage a fight - but seeing so many opportunities pass by because you were waiting for an apparently unrelated cooldown (Highlander) seemed counter-intuitive for the build. Highlander now has a passive/active component - the passive restoring basic cooldowns on kills and assists - while the active keeps the speed benefits that the original highlander had. Note, however, that Highlander will not reset itself passively or actively. Quote:
Double Strike Double Strike was operating in a burst paradigm that seemed anti-thesis to the continuous threat pattern that we wanted to build up - Especially with Alpha Strike becoming a larger part of threat for AD - this spiked his assassin pattern to an unhealthy level. Double Strike has been retuned as a building-up paradigm. Every 4th attack, Master Yi's next attack will strike twice for 100% damage and 50% on the second hit - but he must use this additional double strike within the next couple of seconds - This also had some neat synergies with the retuned Alpha Strike and Wuju Style."

More on Alpha Strike / Q:
"Alpha Strike's bounce range is 600. Added the UI secondary radius indicator on Alpha Strike.

Alpha Strike will now prioritize the closest target that has not already been hit by Alpha Strike."

Ququroon on keeping the swords on Master Yi's boots:
"We have elements on our champions that are very iconic, and very dear to that champion in general. Karma's fans is a very strong example of this that we learned from. For Master Yi, we saw no reason to remove them. They add a tiny bit of visual clutter, but for the most part, we would be making the champion more generic by removing them. They add to his fantasy, they add to his silhouette, and they add to the thought that this dude has so many swords that he's truly a master of his own style.

Additionally, did you know that the swordboots/bootswords/shoedaggers only appear on Base and Assassin? We kept this the same."

Solcrushed also had a few things to say:

When can we expect these Yi changes?:
"Definately not 3.9 (next patch) but hopefully not too far off!"
On itemization with the new Alpha Strike changes:
"Alpha can both crit & gets reduced cooldowns with each basic attack. Even with more emphasis on Alpha, AS/Crit does not lose its appeal, while flat AD becomes at least conceivable."
Will Alpha Strike apply on hit effects?
"No, that is pretty much stealing Fiora's thunder and clunking her on the head with it."
Can the second hit of E crit?
"Yes, it is an autoattack for all purposes other than dealing half damage"
Does he still lose the passive bonus on E when it's on cooldown?
"Yes, we tried it staying on and it made the skill completely mindless while taking away the coolness of the reset happening."

Riot Entropy also mentioned the old Master Yi Voice actor is returning for the update!
"We brought back his original voice actor. You're good.

Oh, and someone was asking about the taunt. He's still got it. We wanted to preserve most of the lines people expressed attachment to in addition to expanding the script."