Hi so this is my first guide. Decided to write a guide about Kayle. Kayle has a generally mismatched kit. This is however very useful since it allows you to hit a broad range of functions. This build lets you be a support/dps.

Pros

Kayle is mobile due to her Divine Blessing.
Kayle has natural splash damage.
Kayle is able to be a support or a damage dealer, as well as play hybrid.
Kayle is able to push and farm easily.
Kayle has early harrass.

Cons

Unfocused kit.
Weak innate.
Average stat gain.

This build lets you be a support fighter which is what her kit is supposed to be. Kayle will be able to give out a decent amount of healing as well as the ablity to shred and destroy targets very quickly one on one. You will usually anchor yourself to your team's tank or to your team's carry. If you can actually manage to finish the items, switch out your boots for berserkers to hit faster.

During most fights, you will be both healing and shredding. Shred the target your tank wants your team to focus. You will have two snares due to Reckoning and Hextech/Bilgewater. Your heal should generally be used on your tank as he initiates. Intervention should not be used to save your teammates from death, but rather to make sure they don't get to the point where they need to survive. Mostly, use it immediately on your tank or your main damage to let them soak up a few spikes early game.

Ghost is very functional for offence/defence to heal or chase or run depending on the situation.

Ignite is a great finisher, and can be boosted using Reckoning. Similarly, using Intervention, you can tower dive, Reckoning and Ignite for the kill.

The runes and mastery allow you to start with 3% Vamp, and 6% Spellvamp allowing you to lane long without needing to go back to town early. The destruction runes give you an early armor shred that when added to items like Malady and The Black Cleaver, allow for moderate armor ignoring. Add in your Holy Ferver, you will be dealing True Damage to lower resistance targets or very close, as well as weakening tanks for your team to destroy.

Glyphs of Force are there to allow for you to lane longer as well as scale with your Archmage and Blast Masteries to allow you to get base items early so that you do not need to rush B.F. Sword. If you can rush the B.F. Sword, all the better.

Finally, Vitality Runes. Hp is important. You will get focused a lot once the other side realizes what you are doing. Sometimes Intervention will be available, usually it won't be. As such, a bit of extra health is always good.

Doran's is a great starting item, and I usually keep it for a while. Nashor's+Ionian give you max cooldown which is great. However, once endgame, replace the Ionian with Berserker's since you will have max cooldown from the elixir anyways. If you are confident you can maintain Blue, replace Nashor's with Phantom Dancer.

Malady and The Black Cleaver are your main sources of damage. These allow you to shred your target's armor, and increase your attack speed.

Rylai's causes your attacks to snare. AOE. Not to mention, extra HP :)

Hextech Gunblade give you both Vamp, Spellvamp, and a second pin point snare. Pair it with Reckoning and you get extra damage. :)

Take Righteous Fury first as it allows you to farm minion waves easily as well as poke your enemies from the back. Assuming no other skill is used, you will not notice the mana cost. Righteous Fury is maxed last, as upgrading it increases your splash damage. This scales directly with attack speed and at low levels, you attack pretty slowly.

Reckoning is maxed first since this is your spike as well as snare.

Divine Blessing is maxed second. This allows you to chase as well as escape. End game, it provides a decent amount of healing as well. Very versatile.

Intervention is your ultimate. I prefer using it to prevent spikes rather than saving allies from death. Most allies will either get chased down anyways, or seeing that they are invincible, try and go back into the fight with too little health.

When farming mobs, early game you can last hit easily, but if you are laning with your carry, just splash damage mobs. Only last hit if your carry can't keep up. Mid game, you should be able to clear large waves very quickly, just keep your Righteous Fury up all the time when you have enough cool down reduction.

I bring Ghost and ignite for running towards allies to use Divine Blessing or Intervention. Ghost can also be useful for escaping.

Ignite works well with Reckoning since it benefits from the extra damage.

Clairvoyance is great for checking bushes and avoiding ganks.

Exhaust works well with Reckoning allowing you an extra snare.

Flash is all purpose. nuff said.

Promote is interesting, but not very useful.

Surge is great for early damage spikes as well as late game spikes. The ability boost helps as well for Righteous Fury which scales on attack speed.

During team fights, use Intervention to prevent spikes and soak up damage. It should not be used to save someone from death.

Divine Blessing can be used to chase as well as to heal, you will have a decent amount of ability power letting Divine Blessing provide a good heal.

Reckoning should be used early to add extra damage and due to its fast recharge due to your cool down reduction, you can use it with Divine Blessing to chase and finish off enemies.

Righteous Fury should ALWAYS be on and you should always try and hit as many enemies with Righteous Fury as possible.

Overall, Kayle is a great support/fighter and has a lot of versitily in her role in a game. She can be a healer, AS as well as a great initiatior thanks to Intervention. Enemies will under estimate Kayle's survivability due to Intervention allowing you to defend as well as attack even at low amounts of health. Great chasing ability as well as decent offencive.