Welcome to an in-depth description and build guide to my personal favorite champion, Akali, The Fist of The Shadows.
To start off, let's describe Akali for what she is.

Akali, the Fist of the Shadows, is probably the single greatest burst damage dealer in the game, bar none. She is what I like to call 'repeat offender.' She can burst multiple times in a short span, decimating weaker enemies and substantially weakening tougher characters. Akali is an anti-everything. In the right hands, with the right build, Akali only needs her teammates to distract the enemy while she deals ungodly amounts of damage to everyone around her, all the while healing for a large amount of life with each hit. There are two times when Akali is not a major contribution to the team.

Akali requires the support of her team early in the game (and later too, but to a much less degree) to get enough gold to become an unstoppable force that she becomes later in the game. She is fairly weak early game to her low health and melee range attacks. If the player is not careful, they become easy pickings for enemy ranged champions. If your team is not playing well or they are not playing as a team, you will do very poorly the whole game. If you lose, 95% of the time it is because your team could not work well together or were all-together garbage.

The other is CC. Akali has a very bad slow for cc, and that is it. However, she is extremely susceptible to stuns. Akali has little escape ability. 1v1, she can get away no problem, but against a whole enemy team, she has no chance. Mercury Treadsand Flashgive the player a better chance to avoid these things, but if Akali is stunned early in a team fight, it spells disaster for the team.

Pros:
Akali is an excellent anti-DPS/anti-mage. She does a large amount of damage in a short amount of time, so she can destroy mages before they have a chance to deal much damage back. Her Twilight Shroudability ruins most DPS simply because it causes them to lose a target for auto-attack.

Akali has great gank ability. Shadow Dancelets the player basically teleport to any ranged champion. What the enemy thinks is a 2v3 quickly becomes a 3v2, as Akali has killed the weak one in the back.

Akali has great staying ability mid-late game. Her healing ability from her passive allows her to run off at low life, jungle for a bit, and then return at near full life to continue wreaking havoc.

Akali has amazing chase ability. Shadow Dancehas great range and allows you to shoot to a fleeing enemy's side. Once you get Rylai's, you will have even better chase since your abilities will slow the enemy. Only champions like Ezrealor Kassadincan escape because of their teleport.

Akali has EPIC SIDE BOOB!



Cons:
Akali is, no matter how you build her, always going to be very squishy. Even with Rylai's, you still only have 2455 health at 18. This is easily shredded by mages or dps should they set their sights on you.

Akali is generally a weak team fighter. She has no cc, and can only focus on weaker enemies. She is a one-target fighter.

Akali's Twilight shroud, which anyone who plays Akali comes to use it like second nature for escaping or scouting, is completely useless to Oracle. Unfortunately, unless you are paying very close attention, your day will be ruined when you throw that cloud and discover that you are not safe.

Akali is notorious for kill-stealing. Shadow Dancemakes this very easy, since you start using it like second nature when you see an enemy at low life. This seems ok for you, but it pisses teammates off, and, as I said, Akali needs her team.

Lee Sin. Everything about him is anti-Akali

Runes:
I go mostly flat AP runes in the seals and glyphs to trigger her AP passive, and Greater Mark's of Strengthwith 1 Greater Quint of strength to trigger her AD passive. This allows you to buy any item you want early game, since both of your passives have been triggered. This helps majorly early game, and you have more than enough AP and AD late game to win without scaling runes.

Masteries:
I go a standard mage 9-0-21 build, with the boosts to flashand exhaustthere instead of clarityand ghostor whatever. I find that the movement speed boost allows you to run around without having to buy the tier 2 boots for a while and the summoner spell cooldown allows you use flashto escape more often and exhaustto ruin DPS.

Items:


Core Items:
Hextech Gunblade
1:Gunblade = Survivability for Akali. Her passive allows the AD and the spell vamp to stack with each other, allowing her to heal for good amounts with each ability. The AP gives extra oomph and the life steal is just nice for your basic attacks.

Mercury's Treads
2:Akali gets CCed out the ***. Simply put, without these, you will be susceptible to 3 second fears and 2 second stuns. With Merc Treads, you at least stand a chance.

Lich Bane
3:Lich Bane = massive damage from Mark of the Assassin. Period.

Rabadon's Deathcap
4:Massive AP makes late game possible.

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Optional Items:

Heavy AP Build:
Mejai's Soulstealer(Before Lichbane)
1:Mejai's is the best AP item in the game in terms of price and AP. However, it is the only AP item that loses AP with your death. Get it only if you are doing well.

Void Staff
2:Magic resistance is bad for Akali. This solves that problem, but there are better things to get in my opinion.


Resilience Build:
Rylai's Crystal Sceptar
1.Rylai's = Health and AP. What more could you want in an AP build?

Guardian Angel
2.By the time you come back with GA, your bubble is off of cooldown. Juke time!

Banshee's Veil
3.Extra MR against pesky nukes, extra health, and a block against a CC.


Regular Build:
Extra Hextech Gunblade
1.With this and Rylai's, you can solo Baron.

Rylai's Crystal Sceptar
2.See above.

(The ironic that I build Katarina nearly the same way, just in a different order.)

Abilities:
Passive: Twin Disciples:
This is Akali's lifeblood. Her entire build and play style is built around both of these. The healing ability of the AD portion of her passive allows her to heal a large amount, allowing you to stay in fights against tanks or high health DPSers. The damage scaling of her AP allows her to avoid becoming a one dimensional champion. She becomes almost impossible to stack against. Stack armor, and her magic damage rips through you. Stack magic resist, and her physical damage will punish you.

Q: Mark of The Assassin:
This is your best friend for your active abilities. Mark of the Assassin is your highest damage dealing ability. When combined with Lich Bane, you do 370-ish damage with the activation of the ability, then with the follow up, you deal your attack damage (230) plus the above damage (370) plus your ability power (600) Grand Total = Approximately 1570 damage in one second. It also has good harass ability early game, throwing at the enemy when they get close. Even without the follow-up, you still deal some damage.
Priority: 2


W: Twilight Shroud:
This is one of your least used abilities, most likely only using to ruin DPS or escape. It is easily ruined by Oracleor enemies camping around it. However, it is useful for slowing pursuing enemies, slowing enemies pursuing an ally, or using it to scout bushes. If you have the chance, use it to extend bushes. This makes it so enemies don't know whether you are actually in the bush or just running around in circles in your shroud.
Priority: 4


E: Crescent Slash:
This is your main farming/life gain ability. Because it technically deals a massive amount of damage when you are around minions, you gain a lot of life from Akali's passive. Hitting all the minions around you to about half life and then using Crescent slashto finish them all off at once is a good farming technique. This is less useful in battles against enemies, but it is an intermediate when waiting for Mark to come off of cooldown. I have noticed that it often does not set off Lich Bane, maybe because it applies on hit effects. It does apply Rylai's100% of the time though.
Priority: 3


R: Shadow Dance:
This is your initiating ability, chasing ability, and escape ability. Use to spring upon the ranged carries to deal with them quickly, or use it to chase the wounded enemy as they run, allowing you to finish them, or even use it on an enemy minion ahead of you to escape from an enemy more quickly. These regenerate fairly quickly, and deal decent damage, so don't be afraid to use it to deal some extra damage on a jungle boss or something. It is also useful for kill stealing should you go down that path.
Priority: 1

Spells:
Abilities that work well with Akali

Heal(She is squishy)
Flash
Exhaust(Wrecks DPS and slows a target in order to kill them)
Teleport(allows for quick B-to-base and also good for ganks)
Ghost(Amazing spell as it is, chase and escape ability improve with this. I find it weak to CC, as Akali already is.)
Clairvoyance(This spell can be used to reveal the jungle and use Shadow Danceto escape from enemies.)
Cleanse(Rids yourself of CC!)

Spells that do NOT work with Akali
Clarity(Obviously, Akali does not have mana.)
Revive(Really not that great of a spell in general)
Fortify(Good spell when used right, however, Akali is not a defensive champion)
Ignite(If you need ignite as Akali, you are doing it wrong)
Rally(Pretty useless spell IMO)

Smiteis a jungler spell. Akali can jungle decently well, but I prefer more useful spells later in the game. If you jungle, you need this spell, but if you don't, don't grab the spell.

How to play:

Early Game:
Start out with an Amplifying Tomeand a health potion. The tome is essential because it build into so many other things. Mejai's become easier if you are doing well, and Hextech Revolver is cheaper if you aren't. Be very cautious against ranged or stealth enemies, since Akali's low life is a target. You WILL be targeted early game simply because of your life total and the fact that Akali is godlike if allowed to build.

Harass the enemy with Mark of the Assassin, mixing in Twilight Shroudto get close and Crescent Slashto farm minions. Be sure to target the champions who cannot gain their life back so easily. If you are feeling overwhelmed by your enemies, do not be afraid to go back to base or ask to switch with an ally.

Your first item upon the first return to base is the basic boots of speed. This allows you to not get outpaced so quickly and allow you to escape enemies. After the boots, focus on getting Hextech Revolver, Hextech RevolverHextech Revolver's spell vamp works nicely in letting Akali regen some health. It builds into Hextech Gunblade, which make's Akali's healing ridiculously good. If you are doing particularly well, get Mejai's soulstealer.


Mid-game
Never, EVER, even if you feel like you are god already, go for sword of the occult. Since you probably have a Mejai's at this point, a SoC is just begging to be ultra targeted. Stay away. Once you have Revolver, as well Mejai's Soulstealer, you should be able to 1v1 anyone but the tank and win. Remember, travel with a buddy and gank often. The more kills Akali gets the more godlike she becomes. Focus on killing enemies and taking the first row of towers. Don't be afraid to grab the Lizard Buff or the Golem Buff. The Golem Buff does recharge your energy faster and shortens the cooldown of your best buddy, Mark. Focus on getting Lich Baneso you can seriously wreck your enemies.


Late Game:
By now, you should have at least Deathcap. Be aware, you should never initiate a team fight. Follow in behind your tank and wait for your mages and DPS to wear down the enemy before jumping in to finish off the squishies. At this point, Lich Banewill allow you to take down even tanks with a little help, so don't be afraid to target them as well.

Akali is a difficult choice in ranked play. She had little in the way of Crowd Control. She does heavy damage, but is often too squishy to deal with the heavier hitters. She really can only fill the role of either a clean-up champ or an anti-carry. Clean-up because she is good at taking down enemies with low health fairly quickly, and anti-carry because her bubble and crazy high burst damage allows her to escape high damage AD heroes like Xin and Yi as well as preventing her from being targeted by Nukes like Malzahar or LeBlanc. She has no other large function in any game, since she is not a pusher, nor can she stand for long in a team fight.

There you have it, a proper guide to Akali. Remember, wait to initiate, don't be afraid to jungle, and abandon your buddies if they are lost causes. There is no shame in living to fight another day.

"You know, we probably should have been focusing Akali. She was massacring us. Everyone just hates Amumuand Olafmore, I guess."