Okay, my experience with Kayle, has been fun. I've played around with multiple play styles, I.e, Pure AD, Pure AS, AD/AS, AS/AP, Pure AP, AS/On-Hit-Effects. My favorite at this point is definitely AD/AS, for the simple fact that while Kayle's Q can be pretty damaging to an opponent not stacking health, her true power is in her E ability.

There's a reason to the order of items I've listed. I always prefer to go (Kage's Lucky Pick > Philosopher's Stone > Nashor's Tooth > Ionian Boots > Stark's Fervor > The Black Cleaver > *Sell Philos Stone > Phantom Dancer *or w/e you feel you're lacking at this point).

I start with the Kage's Lucky Pick for the simple reason of the Gold/sec, and AS. It's relatively cheap. Following that up with Philosophers Stone, It's cheap and the Health/Mana per second are a nice bonus to the Gold/sec. I love the Nashor's Tooth for these reasons, +50AS, 55AP, 10mana/5sec, 25% CDR. I follow this with the Ionian Boots, to cap off the CDR and the movement speed, on the cheap. Stark's Fervor is nice, I'm sure there's better and if there is please let me know I'm always looking for new ideas on builds/strats, but I like it for the 20AS, 20% AS, 20% Lifesteal, 30health/5sec, -20 Enemy Armor Aura's. I mean the benefits here are just amazing. The Black Cleaver I placed in here to get that extra AS and to finally add some AD, I know the AD is LACKING to this point and this one item cannot make it up, but it's worked just fine for me so until I can seriously review and test a replacement item I'm going to continue to count on it :D, 30 AS, 55 AD, and the nice part: On-Attack: Enemy armor -15 for 5 seconds, up to 3 stacks. Total Cost at this point 10,915 Gold.

As the game moves on into the last stages, I'd suggest replacing your Philo's Stone with either a Phantom Dancer, or possibly something AD heavy, as at this point your philo's stone has outlived its usefulness. AND IF the game continues even further obviously upgrade your kage's pick into something more useful than +20% AS.

Now I'll give a review on the overall outcome of doing these items.

Total AS Bonus: 140%
Total AD Bonus: 55
Total AP Bonus: 55
CDR -40%
Lifesteal: 20%
ManaPerSecond: 3.6 or 18/5sec
HealthPerSecond: 9.6 or 48/5sec
Enemy Debuffs: Stark's Fervor (-20 Armor Aura)
The Black Cleaver (-15 Armor/attack 3 Stacks MAX lasts 5 seconds)
Holy Fervor (Kayle's Innate Ability) (-3% Armor/Magic Res./attack 5 Stacks MAX
lasts 5 seconds)
The AS I average at is a little over 2 hits per second. So. Within 4 Seconds (4 Seconds has an important key role in this build/strat) I've hit a champion 8 times, their armor is now looking like this: (-20 Aura(-15/hit * 3)(-3%/hit * 5) = -65 Armor + -15% Armor (impossible to know the exact armor for an infinite amount of scenarious :D) but you see the benefit. Also noting a -15% magic res. as well.

Now after reading up on the Items Chapter I'll continue on. The importance of the 4 second Rule, Kayle's Q ability "Reckoning", not only deals initial damage, but slows the target's move speed by 35% for *4 SECONDS*, now during this *4 SECONDS* Kayle will deal +10% damage to the target Champion. Oh and the initial hit is: 260 + (AP * 1) + (AD * 1), so its a nice hit to start with.
OK now the run down, find a target, (Pop E, "Righteous Fury" > Pop Q "Reckoning" > Spam autoattack until Reckoning is up, pop Q again. It will take around 5 seconds before you can use Reckoning again. The 4 Second Rule comes into place between your first Reckoning and your second. After Reckoning 1, you will be auto attacking for 4 seconds, at 2 hits per second. 8 hits. These 8 hits will be boosted by your Righteous Fury and the +10% dmg from Reckoning 1. Time for some numbers.

Run in: Pop Righteous Fury > Pop Reckoning (260 Base + (55(AD)) + (55(AP)) = 370dmg & +10% dmg > Auto attack for 4 Seconds, 8 hits. Each hit under the effects of Righteous Fury are: AD + 60(AP*0.2) This build has only 55 AP, so the total per hit is = 226.9 + 10% dmg IS 249.59; Splash dmg to any nearby minions/champions: 40% of AD + 60+(AP*0.2) = 133.36 Not really a whole lot of dmg right? welllllll, 8 hits later what do we have? Grand total for 4 Second Burst: 249.59 x 8 = 1996.72 Direct Dmg, 1066.88 Splash Dmg, If the champion is still alive after this slap him/her with another Reckoning for 370 Dmg and repeat. That's about the gist of it. None of these numbers included the benefits of replacing the Gold/sec items from the beginning. All this not including the Armor/Magic Res. Debuffs.

All numbers are based on Level 5 Abilities, as I would not write a guide for abilities that weren't capped lol.

Oh, the Gold/Sec with both items and based gold gain rate comes out to... 2.4/second, 30min match = 4320 Gold, if the fight drags on the gold just increases further.

Please no rude remarks or anything of the like, this isn't a be all to end all guide it's just what I've tested and what's worked for me, and like I stated earlier if you know of a better item, strat, etc. let me know :D. Thanks, Goodnight.