This is a basic build to Akali, my favorite settings with her, it probality will not be the best guide/build for her, but still my favorite. Mastered in Ability Power and a little bit of spell vamp to survive in lane or in hard situation or to get buffs without losing your life. I need to thank you for starting to read this guide, I hope to be effective to you and need your patience because english ins't my main language, and I haven't a good english. I wish to you a good game with this guide.

Runes are basics too, x9 Greater Mark of Magic Penetration for her skills wich uses magic, and x9 Greater Seal of Ability Power, Greater Glyph of Ability Power, x3 Greater Quintessence of Ability Power for try to fed at begin of the game. It will result in 29,07 plus 8,55 magic penetration.

So, here we have 10/20, I not use 9/21 because Tenacity isn't better than Burning Embers for her. How I said in Runes, she start 29,07 Ability Power from runes, plus Burning Embers it will be 39,07 just from these two things when your Ignite get cooldown.

Also have the Cripple wich gives 10 Magic Penetration, plus your runes you'll have 18,55 Magic Penetration in start of game.

Spells is more important than you think, we all know it have a great cooldown, but it can be used at first level to make a good damage with your masteries help.

I prefer to use the two masteries wich is in top of this guide.

Exhaust
For 3,5 seconds the enemy will make less damage, will get a 40% less speed, and you can make more damage because the masterie, you'll be able to be higher than your enemy, it will be like much more stronger than him.

Ignite
We have it for 5 seconds, making 50 damage plus 25 each level you have, so at first level we have 75 damage each second, it results in 375 damage, and it's a real damage because the magic resistance will be ignored.

But we have others spells wich I'll explain my point of view:

Flash
It's a spell wich can provide you a good movement trough the walls, you can escape with it or you can get your enemy, also don't forget your Shadow Dance so you can use Flash and Shadow Dance to get the enemy, or to escape using it plus your Shadow Dance in jungle monsters, can be a incredible spell.

Cleanse
Prevent you from stuns stuns, slows, taunts, fears, snares, sleeps, silences, blinds and immobilizers, also if you use it wrong before that things, dont worry it'll reduce the duration of newer applied ones by 65% for 3 seconds, or you can use to prevent something, you know what to do, but I have never used it for Akali, the choose is yours.

Ghost
Give you a status of greater movement speed wich the durations is 14 seconds, can be a good spell, but remember you have Shadow Dancer, but still good for running faster to other location, like turret from turret, or your base for their turret or escape from fights and such more

Rally
Well, this isn't a good spell, but still working for her with you have the masterie for it, can be provide for you ability power if you have that, I haven't many comments to this spell, but I don't think it can be a incredible spell. BUT, think about it at level 1, the ammount you can gain at first level.

Heal
Gain health point is a good ideia, but I like to kill enemies more easily instead to gain heal at the fight, but still working for her and isn't a useless spell, also so many people think different.

These spells over here isn't for my guide or these spells is just crazy to take.

Smite
If you're searching for a jungle Akali, don't read the rest of this guide.

Clarity
Are you crazy or something like this? If you want to b useless to yourself take it.

Promote
Seriously, who uses it?

Revive
No?

Ok, those all settings provides you a good start, but... We need to get more ability power, so I start with Amplifying Tome, will give to you a good ability power, so you'll have 49,07 and if you have Ignite on cooldown, your Burning Embers will be activated, so will have almost 60 of ability power, don't forget about Cripple.

When you have 825 gold, you'll be able to return to base as soon as possible, you'll have to buy Sheen, a important item to you, return to lane and you can give a surprise to the enemy.

Boots after this to have your base movement increased and more ability power with other Amplifying Tome, at this time Akali will be probality level 6, it's the reason you can buy a Amplifying Tome istead closing your boots to Sorcerer's Shoes, you just buy it after the Tome, when you got money to Sorcerer's Shoes and Hextech Revolver you return to base and buy these two items, so you'll have a good movementation and a good spell vamp. But, the enemies will be posible to escape from you, then the item you can choose to buy is the Rylai's Crystal Scepter so it will slow your enemy to crush them, also you have the Twilight Shroud to slow them and increase your armor and magic resistance.

The next important items you can close without important of purchase order is Rabadon's Deathcap and Lich Bane for next you can buy Hextech Gunblade, and use it to slow enemies from distance, or simple to burst them into a combo.

Void Staff
He have here a good Ability Power and if you are in trouble for making damage in champions with high magic resistance it'll reduce 40% from their resistance after your magic penetration items. and 40% from 150 is 60 then the final resistance is 90.

Mejai's Soulstealer
Mejai is for a good start game wich need you for killing or get assist to get a high Ability Power, it can provide you for a sick OP Akali, and making any champions hit the ground at mid game.

Abyssal Scepter
If you die too much in game for champions wich uses AP, you can use it to prevent that, and it gives to you AP and resistance reduction wich is really good for more burst damage, not just for you but for your entire team, but forget if you team isnt magic base damage.

Zhonya's Hourglass
Good item instead Abyssal Mask if you're having trouble with physical damage, because it provide you a good armor and gives a status of unkillable for 2 seconds.

Mercury's Treads
Just a little more of magic resistance and resistance from debuff.

The best part of my favorite build is because she is a burst damage combo, you can stay throwing her Mark of the Assassin to enemie and when you decide to make a little burst damage you throw it, wait for the cooldown, use your two spells wich is Exhaust and Ignite and start to use Shadow Dance -> Physical damage (Normal hit) -> Mark of the Assassin -> Physical damage -> Twilight Shroud -> Wait for the mark cooldown and repeat the combo. Also you can use her Crescent Slash if you want, then it will can be after the physical damage you'll add it and do a normal hit again because the Sheen or Lich Bane.

How you can see it, this build is about not just from items, but also a good help from your 2 spells, runes and helping you to masteries and the combo, it can be incredible a combination for killing from a burst damage.