Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Before reading this build at all, you must first understand that I'm aware you can't have the 6 items and Doran's Blade. Doran's blade is just a good start. Second: The stats are off a bit. In the end game you will actually have closer to 600 ability power, 214 attack damage, 24 armor penetration and 0% crit chance... It's also Important to understand that the items to get to the final tier items aren't stated because order does matter based only on who you are fighting and how well you are doing. Items may even change based on what build the other team is going. THIS BUILD IS VERY ADAPTIVE. The idea to this build is to basically take on any one person at any time, and putting most of your durability into restoring health through lifesteal and spell vamp. The strategy is to not go flying in and immediately popping Twilight Shroud, but to play conservatively. When team fights arise your main goal is to Shadowdance to the back where their most important enemy champ is (e.g Sona, annoying Twitch, etc) so this build relies heavily on knowing who to take out first. Do it right, this build can take on anything at any time. This will even allow Akali to mid early game against most champs.
(P.S I tried to make this build once before, but I wasn't signed in so it got turned into "made by guest" and can't be edited, so I made a new one)
Runes and Mastery
Basically the idea here is to grab both of Akali's passives as early as possible without sacrificing survival and other important runes.
Ability power Glyphs and Quintessence: At level one you will have roughly 14 ability power. Although this may not be enough to get the magic damage passive early, you should be able to grab it if you use Ignite, putting you at 24 AP because of the offensive talent mastery. Why grab a little extra AP? early game it works out well, and in the end why not?
Armor Penetration Marks: These marks go really well for 2 reasons. First: Champs that aren't tanks don't have much armor anyway, and early game no one has this much armor, including the minions. This makes minions easier to farm and champs early game easier to kill. Second: Lichbane's extra damage from AP is physical damage. See below in Item Build for more info. You will have roughly 24 Armor penetration, even more if you switch up items or have allies further decreasing armor.
Health Seals and Quintessence: Good for early game durability/gank resistance, and it's better than dodge runes if you don't have Nimbleness. There are alot of times early game where I get away from fights with no more than 20 health after I tower dived for a kill. You never know.
I usually like to go with Ignite and Exhaust, although Exhaust can be replaced if you prefer another like Flash or Teleport. I only use it because of the Cripple talent so it's good at hammering down AD users such as Warwick or Xin. Because of improved Ignite it will allow you to grab the second part of your passive after using it, plus it can really help for damage and cutting lifesteal incase you run into a Warwick or targeting down a single champ in team fights to make sure they don't heal up.
Skill Selection Order
You get Mark of the Assassin the first time every time. It helps out with last hitting and harassing. After that depends on how well you are doing and who you are fighting. If it seems like you are getting harassed a bit in any lane, or it is difficult for you to harass, invest in Twilight Shroud next. This will allow you to make a sure fire harassing Mark with minimal damage to yourself. If it isn't an issue, grab Crescent Slash next and use it to push heavily and keep your health up, then grab Shroud immediately afterward. After the first in Shroud, keep investing in Mark and Slash every level (heavily focusing on Mark over Slash), and putting points into Shadowdance every time it's available. The reason Twilight Shroud isn't focused until later is because of the fact that early game you only really need the stealth it offers, not the increased armor and magic resist. If an enemy champion invests in oracle early game, then he is either fed or really stupid for wasting his gold, so he has to die quickly.
Item Build Order
When you first begin, grab Doran's Blade for the first part of your passive. This will allow you to stay healthy through the 4% lifesteal and your 10% spell vamp passive. It isn't a huge amount but it helps at first. After that you grab Amplifying Tomb while trying to work up to Hextech Gunblade. After that Amplifying Tomb you work on boots based on how well you are doing, although Boots of Swiftness is preferred. If there is alot of Magic users/disable on the enemy team, invest in Mercury's Treads. If pushing is an issue, grab Berserker's Greaves. If you like running from turret to turret, Boots of Mobility may be for you. If you seem to get yourself harassed a bit, it may be wise to skip the boots for a bit and grab Vampiric Scepter and get the boots right after. After the boots are acquired continue to work on the Gunblade, primarily focusing on the Pickaxe and Bilgewater Cutlass, then grab Hextech Revolver right after. Eventualy you will have Hextech Gunblade. With it's added lifesteal and spell vamp, you can jungle anything at this point. Going into the jungle for a Blue or Red Buff will actually heal you a bit because of the investment in Mark of the Assassin, so you can farm to heal rather than going all of the way home. Use the Gunblades active if an enemy champ tries to run, so this basically replaces the effect on Rylai's Crystal Scepter and the slow on your Shroud until you have them. What you work up to next depends on how you are doing. If durability is an issue, work up to Rylai's starting with a Giant's Belt. If not, try to Grab Lichbane starting with Sheen, with Rylai's soon after. Lichbane's passive effect, movement, and ability power will make taking down stronger targets easier, and will help with your lifesteal and spell vamp (considering your spell vamp is very much affected by your passive magic damage, or at least it was when I made this). You should have at least 250 ability power at this point, so your Lichbane's effect and magic damage passive should be hammering the enemy team. Try working up to Zhonya's Ring. This will bring you up to at least 460 ability power (370 + the added 25% bonus) so Lichbane will be a ton stronger, and the active effect may save you from a few nukes (like Nunu's or Veigar's). The next item is entirely up to you. I prefer the Guinsoo's Rageblade because of the extra damage for my spell vamp passive, boosting me to around 50% spell vamp (35% from passive + 15% from Gunblade), and with the effect from it will help push through attack speed to finally end the long game, plus the added ability power will get you around 125% magic damage from your passive when you have 8 stacks, around 110% with no stacks. You could also grab items like the Void Staff or Abyssal scepter to help with magic penetration, or you could maximize the effect on Lichbane by grabbing Last Whisper, as well as heavy pushing power. Also be aware that at some point you should sell Doran's Blade. Doesn't really matter when you do it, but do it when it's most convenient.
You notice that Lichbane is somewhat relied on when using this build. at this point you should have over 600 (closer to 630, will get even higher with full stacks of rageblade) ability power and 214 attack damage. Assume you have 600 flat, plus 200 instead of 214 for the sake of the argument. Using an ability like Mark of the Assassin will trigger the effect, making your next attack to 200 + 600 = 800 physical damage. But even someone with low armor of say 50 or 60 will have 35% protection, reducing that 800 to 520 (roughly). With the 25 armor penetration, that 50 armor will get reduced to 25, which is more like 20% protection (considering armor value decreases as you grab more). That 520 just jumped to 640 (120 more damage). That is a ton better than +3 damage from stacking .32 damage marks, or the extra 20-40 magic damage from stacking magic penetration (considering that even Shadowdance does nowhere near 800 damage).
Use this build to strike from bushes after your team initiates and take out the weakest/most important/most vulnerable champion on the enemy team by jumping to them quickly with Shadowdance and beating the living snot out of them with Lichbane's effect and Mark of the Assassin (and Slashes and Dances everywhere in between). Do it right and Akali can destroy basically anything within 4 Marks of the Assassin, or less when you use other moves in between and have your team backing you up. By working with your team to take out and control a specific champ (as well as good use of Twilight Shroud) you will have a strategic advantage over the enemy team by being able to flank them without having to go all the way around them.