My first build so please be gentle ;) Hecarim has amazing AD capabilities. With this build, by simply auto attacking, you can be doing approximately 1200 DPS, THAT'S ****ING CRAZY! his abilities also make him a great initiator/ganker/and adds survivability. A good AD Hec will demolish teams.

Abbreviations
HP - Health Points
AD - Attack Damage
AP - Ability Power
AS - Attack Speed
AA - Auto Attack
CS - Creep Score (Minion kills)
XP - Experience points
AOE - Area of Effect
Pots - Potions

Since his first sighting on the northwestern shores of Valoran, the towering, armored specter known as Hecarim struck a chilling fear into the hearts of all who laid eyes upon him. No one had ever seen anything like his titanic, ethereal form before, and the mystery of his sudden arrival was deeply unnerving. When Hecarim began to march eastwards, leaving a trail of desolate, lifeless ground behind him, the villagers of the plains fled their homes for the safety of nearby Demacia. In the city's now-overcrowded taverns, rumors about this inhuman phantom spread in hushed whispers. Some claimed that he was the vengeful shade of an ancient warrior, intent on destroying all living beings; one man insisted that they had seen him leading an entire legion of spectral cavalrymen; others still believed him to be the creation of some hateful necromancer. One Demacian commander, seeking to dispel the terror that had gripped the city, assembled a few of his finest soldiers and rode out to turn back or destroy Hecarim.

The commander led his soldiers to stand in Hecarim's path and braced for his assault. As the apparition bore down on them, an overwhelming sensation of dread gripped the warriors. The men, frozen in fear, could only scream as the ghostly titan ran them down, tearing them apart and trampling them beneath his iron hooves. Hecarim turned to the crippled, cowering commander and uttered a chilling statement: "This is merely the beginning. No mortal army can withstand the might of the Shadow Isles." With that, Hecarim departed, resuming his grim march. Driven to insanity by his nightmarish experience, the commander stumbled back to Demacia, where his dire warnings were dismissed as the ravings of a madman. While Hecarim's origin and intent were still a mystery, his destination became clear when he reached the Institute of War and, in a voice both ominous and commanding, demanded entry into the League of Legends.

"You don't understand... the shadows will consume us all..."
Former Demacian Commander

PROS

-Ridiculous amounts of attack damage!
- Onslaught of Shadows provides a means of escape like a free Flash
-Spamable Rampage for some additional Sheen damage
-Great initiator with both Devastating Charge and Onslaught of Shadows
- Warpath Turns movement speed ---> Attack damage, makes getting movement speed for chasing more viable
-Can chase down champs like a boss (which also makes him a viable jungler)

CONS

-Less HP than most solo tops (since most solo tops are tanks ie. Nautilus Amumu Jarvan IV.
-Pretty squishy late game
- Spirit of Dread doesn't give enough sustain and HP pots are required to stay in lane

Masteries

I believe that the Mastery set up I made is pretty simple and shouldn't require much explanation. The point of these runes is to increase your damage output. I think it's also acceptable To make up for your lack of tanky-ness by doing a 9-21-0 mastery tree; however I feel that the standard AD masteries will wield better results.
I use Summoner's Wrath because it's easily worth it for the bonuses on Exhaust and Ghost.
I chose Sorcery over Vampirism because the cooldown reduction will help massively with spamming Rampage
Lastly, I chose Vigor over Durability because that HP regeneration will really help your sustain early game.

Runes

I decided to take the safe route and pick the stereotypical AD rune set up. I think there is actually hope for the otherwise useless Greater Quintessence of Movement Speed due to Warpath, however 4.5 bonus movement speed only equates to 1.125 Attack damage, so I still feel this isn't worth it.

Other choices (all in quintessence form)
- Greater Quintessence of Health (for additional tanky-ness early game)
- Greater Quintessence of Cooldown Reduction (for spamming Rampage)
- Greater Quintessence of Movement Speed (could be useful, but I think it's a waste)
- greater quintessence of vigor (sustain)
- Greater Quintessence of Life Steal (also for sustain)

Keep in mind when it comes to Runes/Masteries, I personally feel it is greatly based on personal preference, and everything I said should be taken with a grain of salt.

Start of game - At the very beginning seeing as though you're not very tanky, and Spirit of Dread doesn't give enough regeneration to keep you in lane, I recommend Boots and 3 Health Potions to give a small speed boost, and early sustainability.

1st item

- TRINITY FORCE!!!!!! I will admit I doubted the effectiveness of Trinity Force on Hecarim compared to a(n) Infinity Edge, Phantom Dancer, or Wit's End, but I will explain why it's so effective.

Zeal

Zeal is good because when you're looking for more damage attack speed, and critical chance is the way to go (other than flat damage). And the bonus movement speed is good too for chasing, and adds a little more AD.

Sheen

Sheen is good because you get bonus damage for activating any abilities, and since you can spam your Rampage it can add up to a lot of bonus damage.

Phage

Phage is good because it gives some health for more survivability, and more importantly a slow with more AD!
Now add it all up and you get the mother of all items for Hecarim

TRINITY FORCE!!!

2nd Item

- Boots of Swiftness This one's pretty straight forward Movement speed ---> Damage movement speed + Damage = ownage chases and ganks

3rd Item

- Wit's End This is great, it will give a little magic resist for survivability, and Attack speed. It will also add 42 magic damage per hit, which can be up to about 120(ish) per second and that's a lot for only one item.

4th Item

- Phantom Dancer What is there to say? tons of critical chance, tons of attack speed, and some bonus movement speed (and if you haven't noticed the trend, that means more attack damage too)

5th Item

- Infinity Edge This is the game ender. now your critical chance is through the roof and does 250% damage! Not to mention the extra AD you get!

6th Item

- Bloodthirster Can be very effective in survivability with all your damage output, and it also gives some nice damage.

7th Item

- Madred's Bloodrazor Replace your Wit's End with Madred's Bloodrazor For me this item is a personal preferance, it makes getting blessing of the elder lizard (red buff) a snap. It also adds to your attack speed and damage, but most importantly IT RAPES TANKS!!!

- Frozen Mallet is a good item because it gives you HP for survivability and bonus attack damage. It also adds a slow for better chases; however, I don't like it very much because it isn't as good as the other choices above. Yet it's a good replacement if you don't like Madred's Bloodrazor
- Last Whisper This is good for armor penetration, However unless they're stacking armor, I'd avoid it.
- Black Cleaver It gives armor reduction and more AD/AS, so I perfer it over Last Whisper (more info Black Cleaver V.S. Last Whisper) However like with Last Whisper unless they are getting armor, I'd avoid it.

/ - both good if you need more survivability; However doesn't help much in the killing department.

- Atma's Impaler You have very little HP, so it's not worth it.
- Wriggle's Lantern It's basically a weaker less useful Bloodthirster.
- Manamune Doesn't have enough mana (or need for mana) to make this item worth while.

Yay! No unit collision (as a Fizz player, it feels a bit like home) but more importantly now movement speed equates to damage (I tried to take as much advantage of this as possible) I noticed that by the end of the build I had a total of 45(ish) bonus attack damage!

Rampage is a great additional source of damage, especially with sheen, and keep in mind it doesn't stop auto-attacks so it's basically an extra attack. This is why I max it first.
Rampage can be used while farming to take out multiple creeps for more efficient CS
Always use Rampage after initiating a team-fight for the AOE damage.
Spam Rampage as much as possible for extra damage.

Spirit of Dread Is your only means of sustain. Unfortunately it's not very effective, for the mana cost is pretty high for the amount of life you actually get back. Even so it's important to use it whenever you have HP missing, or if you're going to attack a champion.

Devastating Charge is an ability that has multiple purposes, it's like a Swiss-army-knife.
1.) Initiating, you can use Devastating Charge to quickly attack for a good amount of damage and a push in whatever direction you desire your target to go. Play Video /league-of-legends/ability/devastating-charge-487 Play Video /league-of-legends/ability/devastating-charge-487 Play Video
Keep in mind you get pushed with your enemy making this dangerous around turrets It's not like Alistar's Headbutt which just knocks the enemy back.

This is like your second Swiss-army-knife. Uses include:
1.) Initiation, fears and scatters their entire team making solo targets easy prey. Play Video
2.) Chasing, could close the final gap and do the final blow to your victim.
Play Video
3.) Escaping, It's a free flash, you can use it to hop basically all terrain, or smash into your chasers and fear them to give you a leg up in distance.
Play Video

As an AD carry Exhaust is what you use to get a few more seconds of oh-so precious auto-attack.

Usually Ghost is only useful for escaping, and or chasing, but now with new and improved Hecarim you also get bonus attack damage making this summoner spell better than ever, and a must have!

Teleport is my least favorite but if you're not good at maintaining good HP/Mana, or if you just can't wait to get your shiny new toy from the shop, this is the spell for you. Also, since you're a solo top, you can write it off ;)

Ghost is much better because of the attack damage increase, and your Onslaught of Shadows is basically of a Flash anyway.

This ability is more for AP carries, it's better to Exhaust and get more auto attack in.

Perfect for heal-baits, and gives a little more sustain but other than that useless.

The attack speed is nice but the ability power is useless and the benefits are too small.

Great to escape from CC with all your speed, and Devastating Charge it can be a viable escape mechanism.

You're not a support, it's not your job to have this spell

In rare occasions this can work, but for the most part it's useless. Please avoid this spell.

This is only useful if their hitting your base, but if that's happening, you have to solo 5 champions, and all you will accomplish is another death

This is only useful for jungling, and you're soloing top.

Acceptable for noobs that can't control their mana usage but mostly useless.

As a Laner
1.) To defend your turrets.
2.) To stay alive.
3.) To kill the enemy.
4.) To make the other person(s) underfed.
5.) To get CS.

As a Ganker
1.) Not to die.
2.) Use Devastating Charge to knock them back towards your towers (or at least not towards theirs).
3.) Secure the kill make sure someone picks up the kill.
4.) Make sure you're tower is ok.
5.) Push the lane/take the tower.
6.) ???
7.) Profit

In a Team-Fight
1.) Initiate with Onslaught of Shadows.
2.) Kill the weaklings.
3.) Stay alive.
4.) Chase low HP champions.

Your main job this early in the game is to get levels and gold through CS, and Champion kills. The person you're laning against is looking to either smack your face in, or ignore your existence and feed off creeps.

Harassers

If you're facing and enemy that harasses hard, be cautious. You need constant ganks from your Jungler, and a "leg up" on your opponent (a higher level or more items), to keep your dominance over the lane.

Farmers

If he is going for CS then try to out-CS him; however if he starts beating you in CS, then start harassing them, then he will either harass back, or accept submission and hide allowing you to feed harder than Cho'Gath Feasting during thanksgiving.
Why do this? Because late game you will have a higher level and more/better items than your opponents allowing you to rack up kills harder than pre-nerf Shaco.
Try to recall as little as possible, the more you're in lane the more gold and XP you get, and try only to recall when the other person in your lane is gone, or pushed to his turret, you could also use this time to gank mid or bot (if you have Teleport)
Play Video

Ok now it's time to share your gigantic fatness with the other team. Your responsibility here is to make sure your lane is taken care of then run mid/bot/jungle, to grab kills and help with team-fights. During this time, just remember it's great to be fed, but give your AD and AP carries some kills too, for it doesn't matter how fed you are, one Hecarim can't kill 5 champions o solo mio. And don't forget to farm.
Play Video

Do your job to initiate, and help in team-fights, if you have Madred's Bloodrazor make sure you're getting the tank after making quick work of the lesser HP champions. Don't solo turrets, if you want to take a turret down without minions get your tank in there. Don't forget to be getting Red (if the AD carry is ok with it) Dragon and Baron Nashor (with your team of course!).

Remember everyone's fed at this point. Doesn't matter how many kills you have, or your team have, nor does it matter how many kills the enemy has. One good push, one backdoor, or a single ace will cost the game. Be careful and win with good teamwork and great strategy.

This build is incomplete! I rushed this build to get it out ASAP, but there's more to come! Pictures videos and more! Tell me how to make this build even better in the comments, please give feedback! Although I love thumbs up please rate what you think it deserves and if you do chose to down vote please tell me why.

Through 15 minutes of bloody eyes, this guide was tediously checked and corrected by KirkR.