Update 8/12/2011: After some reevaluation, I've altered this build quite a bit.

Changes:
- Lich Bane instead of Deathcap as final item for more MR and on-hit magic damage.
- Altered skill order to keep Reckoning cost down and squeeze what little sustain there might be out of Divine Blessing.
- Flash = Die less. Die less = Don't need teleport.
- Revised Masteries and Runes (pfft, I'm not even 30 yet anyway...)

I picked up Kayle on a whim after the Wukong patch. I wanted to figure out for myself if she was horribly nerfed or just underplayed or even misplayed. I took immediate interest in her active skill, Righteous Fury (Henceforth: RF), giving both range and AoE. This build focuses on RF output, taking early Attack Speed, Cooldown Reduction, Mana Recovery, and AP in Nashor's Tooth and building Attack Speed and bonus Magic Damage and Magic Resist Shred before topping off with a heavy AP item when attack speed is close to cap.

This build is a powerful early pusher, RF tears through minions like butter, but in late game becomes a strong carry and even an occasional initiator.

Righteous Fury is a minion slayer from the start, it gets the first point. At level 1 you're greatly multiplying your damage output with both magic damage and hitting multiple creeps. Probably the most unnoticed feature of RF is the flat mana cost. 45 mana from first to last level.

Your choice of Reckoning or Divine Blessing depends simply on if you've taken damage yet. Work Divine Blessing as a heal early on, but don't rely on it as anything but a speed boost after a few more levels unless you have mana to spare.

One point in Reckoning early gives you utility in the slow effect. The damage isn't stellar but it's still a nice harass tool and lets you initiate and chase with RF for some nice followup damage.

This is when Clarity comes in handy, because Reckoning and Divine Blessing (Henceforth: Reck and DB) will start blowing through your early mana.

I now keep Reckoning and DB equal in level (leading with Reckoning) as they both have fairly equal (read: ****py) utility, so keeping mana cost down in mid-game and keeping both skills relevant is the new scheme.

Finally, building Nashor's Tooth will cut RF's cooldown to about 12 seconds. Pushing it much lower is a bit of a mixed bag since you'll want to tap it before it wears to prevent Kayle's primary problem (running into melee range like an idiot) but you'll encounter a little more mana use and all at the cost of an item slot. Either way Kayle is gonna need a little micromanagement every ten seconds or so in a fight.

Learn the range of Righteous Fury and activate it just as or before you reach it from your target. This keeps your buffer space. You can either use Attack-move when engaging minions or manually target the more central ones, but it's hard to not be hitting all of the melee or all of the mage minions at once. One casting of RF should clean up a whole minion wave before wearing.

Use the classic micro Move->Attack kiting with RF to circle around minions away from other champs while otherwise ignoring them. Can also harass while kiting someone slowed with Reckoning back to your tower.

Once you unlock Reckoning, it has a fairly good range and you can harass with it or even slow an enemy champ effectively enough to really pound them with RF, which does your real damage in the end.

Divine Blessing can be spammed to stay out for longer but it hardly outpaces your base HP regen. If Clarity is ready you can definitely utilize it for some healing but you need to keep some mana reserved for Reckoning's slow and using DB for the speed buff instead. Remember your teammates will appreciate DB as well, both for scooting them out of danger and giving them even that teeny bit more HP.

Intervention's uses are sketchy. Against real players as well as bots most enemies will expect you to use it. I tend to keep it in reserve because of the mana cost, but it has some very specific uses:

- If you turret dive for a kill with RF you can absorb at least one turret blast with it when backing out. Remember that the damage is dealt when the projectile hits.
- Highly predictable Ults like Nunu or Pantheon's can be laughed in the face of with proper timing. Keep in mind it won't always protect you from additional effects like slows and stuns (not that I can comment on why not).
- Some Champs are very predictable and will play into Intervention's best use, such as Annie. Just have a good idea of the range of their abilities and pop Intervention as they rush you. It's highly likely they'll pump everything into your shield and you'll had a juicy slowable target at close range to RF into oblivion.

Boots are an early priority. For a time I was taking regular boots and stocking a few extra potions, but I found starting with a dagger to be better for getting more early minion killshots and still granting one potion (or two, if you wait after minion spawn for the extra 15 gold and teleport out). This lets you go straight to Berserker's Greaves for a mere 500 gold next time you're at the fountain. When in a solo lane, however, Kayle can sustain well enough and farm Minions to gather 1640 gold to get Berserker's Greaves and Stinger in one trip.

Berserker's and Stinger will make a noticeable increase in your attack speed and RF's output. You should now be killshotting most of the minions in a group and can foray into the jungle without coming out low on HP and ineffective.

Nashor's Tooth tends to be a long haul, but branching out into the jungle can start as early as level 5 even if you haven't picked up Stinger yet, just get both daggers that build into it if you can.

At this point you're effective enough in creep farming to make the leap to Nashor's Tooth, and around level 9 you can easily take the blue buff solo (red buff takes another level or two to be safe, because you're squishy).

Piece-up to Malady if you can't do the 1825 all at once, but the order given is focused on farming 1.2-2k gold between Recalls to because you have the sustain to do so. Besides raw attack speed, Malady gives some Magic Resist shred to go along with Kayle's passive and a little bonus magic damage.

Wit's End and Sword of the Divine serve much the same purpose: Attack Speed and bonus magic damage. Wit's will give you a nice booster shot of magic resist (including the on-swing effect which will build quickly for +50 MR total), and the fourth swing for Divine's bonus damage comes 'round a lot. These both build on Kayle's passive and Malady's MR shred. I often forget to activate Sword of the Divine, but I'm not often having at champs who dodge a lot plus RF's magic damage can't be dodged anyway.

Alternatively, if you're up against some serious HP stacking, Madred's Bloodrazor is definitely a good choice. You lose a little attack speed in your complete build, but dealing 4% of your target's health 2.2 times a second definitely makes up for it. Take it after Malady (late enough in the game for HP stacking to have really taken off) but before Wit's End. You'll actually be replacing Sword of the Divine with it, just also advancing it in order too. Wit's End has the higher overall bonus Magic Damage and the MR is rather necessary.

Just note that Madred's Razor costs as much as Wit's and Divine combined and gives only half the attack speed and somewhere around the same on-hit damage depending on target HP. Wit's and Divine will chew through minions or Champs alike though.

At this point your attack speed is at least 2.35 hits/second before runes. There is still a selection of things that could be taken to reach 2.5 cap, but that's only around or less than a 5% increase in overall damage. [strike]Instead at this point I opt for a big AP item, Needlessly Large Rod (and all the entendre to go with it), and build that into a Rabadon's Deathcap if the match truly drags on for that long. This gives a huge boost to RF (roughly 60% more magic damage, despite the lowered AP ratio) and makes Reckoning drop some nice damage as well since by this point it has caught up. This also helps get DB back into being a relevant healing skill.[/strike]

Lich Bane is my new sixth item. It provides a healthy dose of more Magic Resist to keep from getting bursted flat, and the unique passive is activated by both Reckoning and RF, so it will be abused heavily for about 160-180 magic damage on first hits. The smidge of movement speed is nice too.

Watch your minimap. If you see a good mass of minions, get all over it with RF. The larger the pack the more damage you'll be doing because of splash, and the more money you'll get when you're killshotting 90% of them. This seems kinda obvious, but it's difficult to express besides that RF at high levels will chew through a minion wave faster than even Sivir.

Golems, Wraiths, and Wolves all fall easily to RF as early as level 5. Switch to the other golem after 3-4 swings, stand in the middle of the wraiths and attack the blue one with RF active, and open with Reck on the giant wolf for RF to tear it down before it even gets a second attack on you.

At level 14 or even 13 if you've got Nashor+Malady already you can solo the dragon, just spam everything (Even DB on yourself).

Your primary target is going to be burst champs. A scary prospect with only 2k HP, but it's very easy to rush them and pop Intervention just as they turn to burst you. With RF you can still generally maintain the distance buffer for Divine Blessing to be your escape route. Always back off as you drop Intervention to see if the bait was taken or if your target is waiting for it to wear before bursting you.

Don't try to fight heavy melee straight-up, especially HP-Stacked ones. Micro and kite with RF and harass with Reck, but don't get suckered into turret range because RF can wear off and stupid Kayle will run right in to melee.

Pros:
- Very good pusher and farmer to be able to afford the build.
- Strong against almost any target. Few would expect raw magic damage from Kayle.
- Able to harass and kite but still dangerous if you really want someone dead.
- Good base armor means you can survive early squabbles.
- Intervention, 'nuff said.

Cons:
- When Righteous Fury wears off, Kayle will try to run into melee range like an idiot. This skill really needs to be changed to a toggle ability.
- Very squishy. Intervention makes up for it if someone's rushing to burst you, but you're a high priority gank target.
- Rather slow to get going. Building Nashor's Tooth is the biggest hurdle, but then your farming capability skyrockets and the rest of the items come together quickly.
- DB is a pathetic heal, hardly ever more than 10% of your total HP. The speed buff isn't too stellar either.