There exists an ancient order originating in the Ionian Isles dedicated to the preservation of balance. Order, chaos, light, darkness - all things must exist in perfect harmony for such is the way of the universe. This order is known as the Kinkou and it employs a triumvirate of shadow warriors to uphold its causes in the world. Akali is one of these shadow warriors, entrusted with the sacred duty of Pruning the Tree - eliminating those who threaten the equilibrium of Valoran.
A prodigious martial artist, Akali began training with her mother as soon as she could make a fist. Her mother's discipline was relentless and unforgiving, but predicated on the fundamental principle: "We do that which must be done." When the Kinkou inducted her into the order at the age of fourteen, she could slice a dangling chain with a chop of her hand. There was no question – she would succeed her mother as the Fist of Shadow. She has had to do much in this role which others might find morally questionable, but to her it is in service of her mother's inviolable doctrine. She now works with her fellows Shen and Kennen to enforce the balance of Valoran. This hallowed pursuit has unsurprisingly led the triumvirate to the Fields of Justice.
"The Fist of Shadow strikes from the cover of death itself. Do not impede the balance."
Akali was first previewed at the Blog Post regarding the Ninjas:
[...]So, now that we’ve covered the basics, what are some other things that have a tendency to appear in threes? Well in response to the community concerns surrounding Shen's ninja status, we’ve added a Kennen to the mix to promote the spirit of friendly competition. But even with a yordle already competing for assignments with the infamous Eye of Twilight, there’s got to be room for a little feminine energy in any self-respecting ninja organization, right? What the Kinkou Order without a dash of the classic femme fatale, right? Could it be… three ninjas?! Rule of threes!
On May 3rd, 2010 a new preview was given by ByronicHero, the Community Manager:
Summoners of Valoran, the Kinkou Order of the Ionian Isles wanted me to reinforce to you that they are an equal opportunity employer! While by now you've all witnessed the awesome power of Shen and Kennen on the Field of Justice, none of you have yet run afoul of Akali the Fist of Shadow. Which is fortunate for all of you, since ninja academies are really only discerning about one thing: the lethality of their students! And this is one lady ninja who doesn't like to disappoint her instructors!
Twin Disciplines spell vamp ratio increased to 10% per 100 attack damage, from 5% per 100 attack damage, to compensate for the above bug fix. In total, Akali will vamp more from her single target spells and less from Crescent Slash.
Mark of the Assassin: Akali spins her kama at a target enemy to deal magic damage and mark the target for 6 seconds. Akali's melee attacks against a marked target will trigger and consume the mark to cause additional damage and restore energy.
Twilight Shroud: Akali throws down a cover of smoke. While inside the area, Akali gains armor and becomes stealthed. Attacking or using abilities will briefly reveal her. Enemies inside the smoke have their movement speed reduced.
Crescent Slash: Akali flourishes her kamas, dealing damage based on her attack damage and ability power.
Shadow Dance (Ultimate): Akali moves through shadows to quickly strike her target, dealing damage and consuming an Essence of Shadow charge. Akali recharges Essence of Shadow charges periodically, max 3 stacks.