Ahri may not have the best AP ratios out there, but her harass, her spammy-ness, and the number of hits she gets off the majority of her abilities makes her a solid choice for either solo bottom or a part of the windmill team.

Pros:

• High burst damage (especially with Deathfire Grasp)
• High mobility (when Spirit Rush is up)
• Great sustain thanks to Essence Theft
• Has a deadly CC in her Charm
• Massive fox cleavage

Cons:

• Squishy, gets 0 magic resist per level, and starts at only 30
• Mostly skill-shot based. Having an understanding of smart-casting is helpful.
• AP ratios are low because she can hit so many times with single casts. If the enemy stacks MR, you will have to take this into account and buy magic penetration items. Hitting TAB to check the scoreboard is a necessity.
• Current skins are lacking in coolness compared to her classic skin

A fairly standard caster set. Some people will argue that you should take AP glyphs. This is viable as well. I like to spam cast for more damage, and my mana regen seals and cooldown reduction glyphs allow me to harass the bottom lane harder. Marks should always be magic penetration.

I take Ignite and Flash. You can substitute either of these for Exhaust. Surge isn't the best choice due to Ahri's low AP ratios, and she gains nothing from attack speed. Clarity is awful since you can easily sustain your mana without it. Heal might be a viable choice, even with healing reduction a well-timed heal can win fights. Garrison and Promote could also be taken but aren't really optimal. Ghost is just not as useful as flash in most situations.

You will almost always want to open with boots and Prospector's Ring, it gives a good health bonus, AP, and some mana regen. Catalyst the protector is a viable opener as well, since you gain levels pretty fast in the crystal scar, you're going to see the passive activate several times early on. I usually grab one of each potion if I get the ring, and a health potion if I get the catalyst.

The most important item to get is Deathfire Grasp. Some will argue Morello's Evil Tome. It only gives 15 more AP than Deathfire, and Ahri's AP ratios are roughly 33% on most abilities. This translates into approximately 5 to 15 extra damage per spell cast with Morello's Evil Tome. Where Deathfire Grasp gives an amazing active that can drop an enemy's health by a significant percentage. Essentially, you have one more FREE ABILITY that nukes enemies hard. It's not just for use on tanks either. You can drop high damage targets even faster. In my mind Deathfire Grasp is the clear winner over Morello's Evil Tome.

Next up is Rod of Ages. Even if you don't hit the 20 minute mark and max it out, it's always a solid buy. You get the sustain from catalyst the protector plus more health, mana, and AP. This is the second most important item to get. It will keep you alive and let you hit harder. You can sub this out for Rylai's Crystal Scepter, but I find the mana bonus and general sustain is more helpful than a guaranteed 20 AP.

Rabadon's Deathcap is the next item to pick up. It's going to add some punch not only to your spells, but the Deathfire Grasp's power actually scales per 100 AP. Not much else to say about this one, it's a must-buy on most all AP nukers.

By this point, the enemy may be getting their Force of Nature on. If so, you will need to get some magic penetration. Void Staff and Abyssal Mask are your choices. In most cases, I'm going for the Abyssal Mask. It gives flat MR reduction in an aura, boosts your own miserable MR, and gives you a nice AP boost to boot.

If they aren't buying magic resist, Lich Bane and Rylai's Crystal Scepter (which you may have already anyway) are both optional choices if the enemy hasn't gone the magic resist route. Lich Bane for the massive damage it can add to your auto-attacks, and Rylai's Crystal Scepter for the health and slowing effect it gives.

Orb of Deception is always the first skill I max. This is your damage and harass. It deals two hits, and one is true damage. It can wipe out minions masses. It can give huge returns on Essence Theft. If possible, hit enemies at its max range to ensure the second hit. It suffers no damage reduction from hitting multiple targets, so sending it into a group of enemies is great.

Fox-Fire is the second skill I max out. It has great synergy with Spirit Rush. It can give huge returns on Essence Theft. Max it by level 13.

Charm is the last skill I max. This is where good Ahri's are separated from the bad. This is a skill shot that hits the first enemy target in it's path and taunts them but not in the traditional way. Instead of the enemy attacking you like in other champion's taunts, the enemy will walk slowly toward you for up to 2 seconds. It's useful for pulling enemies out of a group, under a tower, and into their death in general. Max it last though because Ahri should focus on damage, not CC.

Spirit Rush is Ahri's ultimate. It's a three-part ult that allows Ahri to dash up to three times in the direction of the cursor. In each jump, she will fire up to three bolts that deal magic damage. Incredibly useful to pick off stragglers, especially when combined with Fox-Fire. Also good for avoiding enemy skill shots and confusing them in general. Take points in this at 6, 11, and 16.

Ahri excels at bottom laning due to her harassment potential. She's also great at top because her charm can separate targets from the group and allow her team to pick them off.