This is my first guide, and by no means is this the end-all always-win Kayle build that will guarantee you success wherever you go. That said, if you give this build a try you're likely to have a lot of fun and do an insane amount of damage. The recent patch was very good to Kayle, in my opinion, and I've had some great success with this build. So if you like what you see or have constructive criticisms please feel free to let me know!

First a bit about me and my playstyle; I'm by no means a ranked pro. I play this game for fun and usually do well but I definitely have my games where I get schooled. I usually tank with toons like Dr. Mundo, Cho, or Olaf and I play more on the cautious side. I don't dive into fights unless I know I or my team can win. When I play Kayle, I can get a bit more aggressive. She can move in and out of battle very gracefully and hit like a truck. You may not always get the kill with her, but you'll make the enemy think twice before initiating a fight with you nearby. I tend to play 3v3s more than anything and prefer not to top with Kayle and this is just preference.

So anyway, about the build. This build relies on heavy attack speed and building attack damage and ability power simultaneously to get the most of Kayle's abilities. This build allows for solo laning, standard laning, and occasional trips to the jungle (not a dedicated jungler by any means!) to be executed quite effeciently. Kayle can gank suprisingly well too; her heal gives her just that extra bit of speed you need to close in and use your snare (which also functions as a damage booster). Her built in AOE damage can waste minion waves and champions en-masse alike (and simultaneously) all while keeping a stones throw away from danger.

PROS

Very high damage output
Great farming
Ability to engage and disengage is excellent
Enemies stacking just armor or just magic resistance will not completely hamper your damage

CONS

A very sleepy build until you get at least up to Rageblade, thus early game may not be the most exciting (or productive).
The order this build takes skills is selfish; you are not going to be a support player at all in the early or mid game

A lot of people are going to criticize my runes; but let me explain why they are what they are.

Kayle can run on just about any sort of rune build. I have 3 rune pages: the one you see above, an all attack speed page, and a melee dps page (lots of armor pen and HP). I've used Kayle with all 3 and honestly this build plays them all well.

Magic Penetration: Magic pen is good because we're already going to get late game armor pen from the Black Cleaver. This makes your Reckoning and Righteous Fury combination hit a bit harder. I also usually see champions try to counter me with magic resistance so this mitigates their advantage slightly.

Health: Extra HP per level is on that page to make it more compatible with other champions (I use this page to tank on Mundo as well). It's not the best choice for Kayle, but extra HP is not a bad decision by any means. That one last hit you escape with just m ight be all you need.

Cooldown Reduction: This is extremely important with Kayle. Getting her cooldowns to the point where Righteous Fury can be used indefinitely is just about the sweetspot in my opinion. That way you can keep a tremendous amount of pressure on an enemy group and force them back or kill them all. And obviously, your other skills will be off cooldown less and you'll have your ultimate ready when you need it most (or your teamate).

Seeing other Kayle builds out there, my build definitely has an interesting skill sequence. While I don't keep engraved in stone by any means, I usually end up doing something similar.

Reckoning:

I sometimes start with Reckoning, usually in 3's. It helps in snagging that first free kill. Otherwise, this skill has 2nd priority to get leveled up. Even though the snare doesn't increase over time, the focus on this build is damage. Reckoning increases the damage you do to an afflicted target which is the biggest draw for me. It also does an uncomfortable amount of damage making it a great harassing tool.

Divine Blessing:

I used to never take this skill until all the others were completed; however I've found taking just one early game gives you that extra bit of speed you need to finish a fight off or get away. Since the focus is pure DPS, heal comes into its own later as a nice bonus. I am always keen to warn my teamates not to expect heals until late game so they are not counting on being bailed out.

Righteous Fury:

While I used to take Reckoning first all the time, lately I start off with Righteous Fury. It's what makes Kayle, Kayle. The ability to put down heavy damage at range AND make it AOE AND make it both physical and magic in nature gives Kayle a very unique weapon. This is my absolute highest priority to level up. Once her attack speed gets up there, Kayle can wipe out waves of minions in seconds and can crictically amplify your team's DPS in a team fight.

Intervention:

Intervention serves two purposes. First off: a bail out button. Intervention has saved mine and others' ***es from ganks more times than I care to count. If you see a nuke coming, put the shield on and let them waste their combo on you for nill. It requires some good guessing and situational awareness to really ward off major damage but when you do, it will infuriate the other team. The second use may sound rather stupid at first, but I've pulled it off before. 1v3ing. Its very situational and usually a bad idea, but if you get ganked by a team (especially squishies) and its late game: your DPS is going to ruin some faces. I have triple killed a gank more than once (usually end up getting 2 honestly) and lived to tell the tale. Doesn't always work, but when it does it will definitely make the other team not want to engage you.