Ahri can use Essence Theft to check bushes and fog of war, when she casts a spell, if it hits, it will grant a stack on her passive or heal her if it is fully stacked, keep this in mind when playing.
Orb of Deception is a boomerang skillshot, meaning you can move after casting and it will change the path of the orb as it comes back. Spirit Rush can be used to help you to lead the orb's return in hectic teamfights; but don't waste the ultimate simply for this purpose unless it's absolutely necessary, as the damage from any single strike of the orb is low.
Do not be deceived by the low damage quoted for Orb of Deception - over repeated applications, the orb deals surprisingly high damage because half of it deals true damage. It is best used when your opponent is walking directly towards or away from you, is standing still, or is at the maximum range of the spell.
Orb of Deception grants exceptional waveclear - the ability to weaken or destroy large waves of minions in a single spell - if you learn to hit almost every minion in a wave with it, which can be done fairly easily with practice. Ahri can beat many champions that she can't in spell matchups alone by pushing large groups of minions at them.
Consider leveling Orb of Deception and Fox-Fire over Charm; this will make you a primary source of damage mid-game, although the lower CC time is a noticeable loss.
Charm, of all Ahri's abilities, is the most versatile, useful, and able to turn the tide of the game in a single play. It is one of the most devastating stuns in the game to be hit with, for it forces a champion not just to be stunned but to walk forward out of safety or cover as well. However, it is a difficult skillshot to connect with.
Initiating with Charm will allow you to maximize your damage, as the target will be unable to dodge Orb of Deception and they will take the brunt of Fox-Fire's damage, all of which is amplified by 20%.
In teamfights, use Charm to divide up the enemy team. Outflank the enemy and pull a member of the team to the side, or use it to pull a powerful enemy champion off a squishy teammate.
Charm can slow enemy champions who are chasing you. Ahri is notorious as a champion who punishes chasing opponents, hitting them with Orb of DeceptionFox-Fire repeatedly while they are charmed, charming them into turrets and team ganks, et cetera. It's also just as useful for enemies who are trying to flee!
Charm is also exceptional at checking bushes for ganks. Cast Charm at a brush and listen for the hit / watch if it stops early. It is better to waste mana and no-one be there rather than to save the cost of the spell and be ganked.
If you hit an enemy with Charm and then leave its area of vision, for example, by walking into a brush, it will no longer follow you until you get into its sight again. The slow persists in any case.
Due to the relatively slow projectile speed of Charm it can easily be dodged if the enemy champion is expecting it. To regain the element of surprise, get into range but lead with a Spirit Rush or Flash and immediately follow with your combo. This both catches them off-guard, and reduces the distance your skillshots have to travel, thus reducing the time they have to react.
Using Spirit Rush all at once may not be the smartest choice in a fight. Try saving them using them to position yourself for your skillshots, chase down stragglers, run away, or to turn the fight with another quick burst to the right champions.
In the early game, Spirit Rush is great for finishing off running champions as you can usually turret dive safely since the skill can be used three times before going on cooldown. However, it is best to save the last Spirit Rush for escaping from turret range if it is used for turret diving. If you've only just gotten your ultimate, this is essential, as turrets will generally kill you in two to three shots at level 6.
Many players see only the offensive potential of Spirit Rush, but it is even better as an escape tool. Don't be afraid to use it to save yourself.
In particular, learn how to Spirit Rush through thin walls - ranked play requires the ability to escape through several walls, or chase a badly wounded enemy through several walls, and never miss a gap closer.
Though Spirit Rush itself is only one spell, each dash will reset the cap of Essence Theft, making it possible to gain up to 9 charges with it when used in teamfights or against minions.
Spirit Rush's cooldown is fairly reasonable, and will be available in most team fights. When in doubt, use it, and if you've made a mistake, use the other dashes to retreat backwards.
Many mages are easily slain if caught by fighters at too short a distance, but Charm andSpirit Rush make Ahri dangerous to any champion she catches off guard, as well as easily able to escape danger. She plays more versatile version of Akali, with both having high mobility and burst. However, Ahri's burst is more suited to tanks (true damage), is multi-target, and she has hard CC, while Akali has greater single target burst and no skillshots.
Ahri 's damage is benefited greatly by her getting close to her enemies. This is why it is recommended that you build items that give a mix of both ability power damage and survivability. Spell vamp and Movement speed are often her best ways to survive, as she is not especially tanky even with high armor. She also burns mana at incredible rates thanks to her damaging and low-cooldown spells, so Mana regeneration is another important stat for her.
For rare games where your Spirit Rush isn't enough to keep you safe, the Spectre's Cowl-Spirit Visage build path grants exceptional magic resist against poke abilities even longer than your own, as well as cooldown reduction and lots of help with health.
Boots help early with Ahri because her default movement speed is slow. You won't get your ultimate until level 6, and even after you have it, you won't always want to waste it chasing down enemies. Boots of Swiftness, Ionian Boots of Lucidity, Mercury's Treads, Sorcerer's Shoes, or Boots of Mobility are all viable boot choices depending on the game.
Ability power is also a must for Ahri. As a fragile mage that needs to get close to output her maximum damage, a health-granting AP item such as Rod of Ages or Rylai's Crystal Scepter may be a good pick-up.
Don't be fooled by Ahri's deceptively low ratios. Rabadon's Deathcap will increase your damage output considerably, as Fox-Fire damage can go up to a 1.2 AP ratio if hitting several targets and a 1.05 AP ratio to up to three targets with Spirit Rush.
Ahri is very often the initiator for teamfights using Spirit Rush and Charm; Zhonya's Hourglass can protect you from an initiation gone wrong by allowing her to turn to a statue while also giving a great deal of ability power damage.
Deathfire Grasp is a common buy on Ahri because the percent damage nuke and increased spell damage lets her destroy one target.
Abyssal Scepter helps Ahri greatly as she will be close to the enemy team in many fights. However, it may be inconsistent at max range since the range on the Abyssal Scepter's aura is 700 and most of her spell ranges exceed that.
Since Spirit Rush's Essence Bolt range is the same as Ahri's auto-attack range, she can deal more damage by dashing towards an enemy and immediately auto-attacking.
All of Ahri's spells can be avoided with proper positioning or juking. Her Orb of Deception and Charm spells are line skill shots that move fairly slowly so you can step to the side to avoid them. Her Fox-Fire and Spirit Rush spells target the 3 closest enemy targets, but do prioritize champions in a smaller range, staying behind minions, tanks, or your team can help you avoid some or all of the damage or make Ahri risk putting herself in a bad position if she wants to damage you with them.
Don't chase Ahri without a very good reason! All three of Fox-Fire's attacks will hit you if you're the closest thing to her, and as soon as you're low on health, she'll Charm and kill you. Wait until Ahri is low on mana or vulnerable, or until you know Charm and Spirit Rush are on cooldown, before chasing her.
Buying health can help you to survive against her true damage.
Always remember to move away from her Orb of Deception path after she uses the spell as the orb will return to her and deals true damage to you.
Take cover behind minions when engaging her in order to avoid her Charm.
When Ahri uses her Fox-Fire, take cover behind minions so the spell will only hit you once.