Hello, my name is Sacritor and I am a 100k Hecarim jungle main with plenty of experience messing around with Hecarim's kit and build over the years since his release. While not the greatest of players I have always been a fan of alternative builds and breaking the meta. So here is my first guide on how to break it, with a sledgehammer.
This build should not be brought into ranked. While it can be successful at lower elos, the high stress environment of ranked will often result in flaming and possible bans for trolling. This build is intended for those wanting to try something different and fun. Just make sure not to have that fun at the detriment of your allies'. Screw the enemy team though, tilt them off the face of the planet with your ridiculous damage and superluminal speed to take them out before they can take even a single step outside of their base.

This build is for those who want a break from the meta, who want to try something a bit more, FLAVORFUL. Do you hate the meta? Do you like assassins? Do you like hurting other people? Do you like rainbows? Then look no further, for I present to you the glorious AP HECARIM!

Why AD Hecarim?

While I love the magical AP pony the AD build does have one thing that AP does not: Rapid Firecannon. This item allows Hecarim to have 573 range at the end of his Devastating Charge, making him able to effortlessly hop over walls with a single basic attack, saving your Onslaught of Shadows for later use in team fights. Stormrazor also guarrantees your first basic attack is a critical strike which Devastating Charge's damage scales with allowing for stupidly high levels of consistent burst damage. If you like GIANT RED CRITICAL NUMBERS then this build is for you. Very little differs from this build's playstyle and the 'standard' AP Hecarim besides the items, so treat them as two sides of the same assassin coin.

Warpath

Hecarim gains AD equal to 15-30% of his bonus movement speed, +2.5% every third level (levels 3,6,9,etc).

While you may be AP, the damage bonus this gives is still great and we make full use of it by getting us much movement speed as we can without going overboard. Ionian Boots of Lucidity+ Lich Bane+ Celerity+ Relentless Hunter+ Ghost+ Devastating Charge=811 movement speed. That is a total of 466 bonus movement speed and 140 AD. With the scaling on your Rampage, Devastating Charge, and Electrocute that equates to 434 bonus damage on first contact.

Rampage

Cooldown: 4 seconds
Physical Damage: 55, 95, 135, 175, 215 (+70% bAD)
Hecarim does AoE damage in a 350 range around him, Rampage's cooldown is reduced by 1 second for 8 seconds to a minimum of 2 seconds if he hits an enemy with this ability. Rampage does 66.7% damage to minions.

This ability is Hecarim's bread and butter, it is what allows him to clear jungle camps efficiently and output consistent damage especially when you manage to finish Lich Bane. Always make sure to time this ability's use around Lich Bane as the damage it provides well compensates the extra half second you will wait in a fight. Learn the rhythm of 1.5 seconds and you will deal a surprisingly large chunk of damage even after your burst combo. Be careful using Rampage early game in the jungle as your mana can get dangerously low making you unable to gank and assist your team when they need you. Max this ability first for its jungle clearing and DPS.

Spirit of Dread

Cooldown: 22, 21, 20, 19, 18 seconds
Magic Damage: 10, 15, 20, 25, 30 (+10% AP) every half second
Maximum Healing vs. Minions and Monsters: 90, 120, 150, 180, 210
Hecarim deals damage in a 550 range around him every half second for 4 seconds and heals for 30% of all damage dealt to targets in the radius.

Frankly this ability is actually pretty bad. On tank or fighter Hecarim it gains its use from being able to keep him alive in team fights but with AP Hecarim the healing is mostly useless besides its use in early game jungling. The damage is also poor late game, giving only 20% AP scaling in burst damage and the rest as DPS over 3 more seconds. Use whenever you can at early levels in the jungle as it is very mana efficient for its damage and healing, and use during your ganks if you have sufficient mana for it and your full combo with some mana to spare for extra Rampages. You can also save Spirit of Dread and use it for its healing in team fights if your team has plenty of CC as it will keep you alive while your team shreds through the enemy. Max last as it scales terribly with level, but consider taking one or two points extra at levels 4 and 5 instead of Rampage if you have problems surviving in the jungle early game.

Devastating Charge

Cooldown: 24, 22, 20, 18, 16 seconds
Physical Damage: 45-90, 80-160, 115-230, 150-300, 185-370 (+50-100% bAD) based on distance travelled
Hecarim gains movement speed over 4 seconds starting at 25% and scaling up to 75% after 3 seconds.
Hecarim's next basic attack during the charge deals bonus damage, gains range (50-250), and knock backs the target (250-450 units) based on the distance travelled but cancels the movement speed bonus.

This ability is what allows Hecarim to be as powerful as he is, the movement speed, range, and knock back all combine together to make for an extremely powerful gank that can quickly close the distance between you and your target, deal a large amount of burst, and knock them back further into lane away from their turret. Always bait a Flash first with this ability, meaning right before you hit your target move a bit to the side in case they Flash that way you do not follow them into turret range or push them towards further safety. If they do not Flash immediately then go in for the kill. Max second for the huge increase to burst and the cooldown reduction.

Onslaught of Shadows

Cooldown: 140, 120, 100 seconds
Magic Damage: 150, 250, 350 (+100% AP)
Hecarim deals damage in a 1000 range line, when Hecarim stops he fears all nearby enemies for 0.75-1.5 seconds based on distance traveled.

MAGICAL RAINBOW HORSE ARMY
This is what really makes AP Hecarim viable. With 100% AP scaling this ability gives a massive amount of burst and locks down a target with fear allowing you to do your full combo uninterrupted. Scarily enough, if you manage to get fed enough this ability is completely unnecessary for instant killing enemies and you can instead save it as an escape tool or use it to reengage the enemy team after picking off a straggler. Use this ability with a bit of caution as it can be blocked by Wind Wall, Flashed away from, and mispositioned if you are careless. Always aim a bit beyond your targets so that they run feared into your team and not the enemies'.

Summoner Spells

Absolutely necessary, while this build can be brought mid lane it does not succeed as well as its jungle counterpart.

If you are unable to use Ghost properly, or just prefer the instant mobility, then take this as your second summoner spell.

The movement speed this spell provides for just 5 seconds at level 1 surpasses the distance Flash would take you. Combine that with Hecarim's damage gain from Warpath and Celerity as well as his multiplicative movement speed bonus from Devastating Charge which further increases all other movement speed bonuses and you have a Devastating combo.

This keystone does the same damage as Predator except it does so 5 times more often, does not require boots to activate early game, does not need 1.5 seconds of prep time, and it does not give away your ambush 4 seconds before hand.

Nearly every Hecarim player swears by Predator, so I am here to attempt to redpill all would-bes and mains alike as to why Predator is garbage on Hecarim and all like champions. See the below chapter, " Electrocute vs. Predator" for the complete math and reasoning behind Predator's inferiority.

In comparison to the above rant, this keystone is much easier to explain. Dark Harvest is poor early game, but scales very well late game. Due to this sad fact it does not properly accentuate this build's strengths of early and mid game domination and so is useless for our purposes.

No contest, best rune of the three as it activates on both Devastating Charge and Onslaught of Shadows.

Strongest vision.

Cutest vision.

Damage.

While a fantastic rune, Hextech Gunblade makes this rune mostly redundant except for early game jungling and so it is much harder to justify taking over Relentless Hunter. However on AD Hecarim since you do not pick up Hextech Gunblade I have quickly become reattached to this rune to cover my health regeneration, ensuring fast recovery from teamfights and unexpected healing when 1v1 against other junglers and fighters.

If you take Predator then yes, otherwise the CDR just for Hextech Gunblade is not worth it.

Beaten out by both Ravenous Hunter and Relentless Hunter so while good it just isn't good enough to justify over these two options.

The flat movement speed bonus scales multiplicatively with Hecarim's Devastating Charge and Ghost giving him insane speed and damage from Celerity and Warpath. If you find the healing from Ravenous Hunter unnecessary then this is a great rune as well.

If your enemies have enough magic damage then consider taking this to give yourself a small health boost in an emergency.

10% CDR is great for this build as you will typically only manage to get 20% CDR from items, and as an assassin and a jungler being able to initiate fights as often as possible is always a plus. However this rune takes up the spot where Celerity is and Celerity is just too good not to go on Hecarim.

638 movement speed, from your standard combo ( Ionian Boots of Lucidity, Relentless Hunter, Lich Bane, Devastating Charge), gives you 88 AD and 29 AP. This adds up 340 bonus damage from your burst scaling, which for a basic rune that's pretty insane. While I love Transcendence, the damage scaling on Celerity makes this thing a beast on anyone who's gotta go fast.

A vastly underrated jungle rune that allows for cheesy ganks at early levels. If you don't care for Gathering Storm and your enemy isn't stacking enough magic damage to justify Nullifying Orb then take this in its stead.

While a nice consideration if you plan on going late game with your team this build is made for early and mid game domination not hard late game scaling, taking this rune is just expecting to lose. Though compensating for weaknesses is a great idea, it is far better to play to your strengths when using this build due to its all or nothing glass-cannon nature.

If your opponents are heavily magic damage oriented or have initiating CC abilities ( Thresh, Morgana, Blitzcrank, etc) then this item can save your life and help in taking theirs.

If you are unsure what to get then Ionian Boots of Lucidity is always good for the cooldown reducation, however in some matches the others may benefit you more. Ninja Tabi for armor, Mercury's Treads for CC reduction and magic resistance, and Boots of Swiftness for slow resistance. Even Sorcerer's Shoes is alright with this build if you feel like adding even more burst. Use your head and pick what is best for your particular match up. Typically finish boots after Lich Bane, either before Stalker's Blade - Runic Echoes or immediately afterwards.

While expensive the damage this item provides as well as its healing is too useful to pass up. The ability to snipe enemies with Lightning Bolt as well as Chilling Smite is surprisingly useful as well. Hextech Revolver is usually best to buy first as it provides more damage for its cost than Bilgewater Cutlass.

Hextech Gunblade just outclasses this item. Since the two items are not compatible and Hextech Gunblade is the superior choice, I never use this item on Hecarim.

An extremely powerful item on Hecarim that helps your burst early game and the long duration fights late game. Build this BEFORE Enchantment: Runic Echoes. Despite its gold efficiency the item scales terribly with AP so buying Lich Bane early insures that you can use your AP effectively. Building Sheen first will also keep your adaptive damage AD early game before it swaps to AP as you gain access to Onslaught of Shadows, so making sure to avoid AP before finishing the item is a good idea.

Standard for any mage or AP assassin, buy as one of your last items.

Stalker's Blade is a fantastic item on Hecarim especially for his assassin counterpart due to its burst damage, speed bonus, and slow which works especially due to his lack of consistent CC in fights. Skirmisher's Sabre in the right hands and against the proper enemy team however is absolutely devastating. Against tanks it completely nullifies their damage while burning through their health completely, ignoring any armor they may have built, and against fighters it can stave off the brunt of their burst just enough to keep you alive to finish them off. While I almost always recommend Stalker's Blade, if you are an experienced enough jungler then feel free to use your own judgement as it is largely a matter of playstyle and personal preference.

Very gold efficient and should always be bought after Lich Bane for the inexpensive boost of AP and burst damage its passive provides.

The ability takes too long to charge up despite its low cooldown and the damage it represents is too inconsistent and underwhelming. Same situation with Predator: on an AP burst champion lacking engage it works very well ( Annie, Malzahar, Vladimir, etc), but for Hecarim it is useless despite its cheap cost.

If your opponents are stacking magic resistance then buy this to counter it, or just purchase as your last item if you find Zhonya's Hourglass and Banshee's Veil unnecessary.

Purchase if your opponents are heavily physical damage or have counterable abilities ( Death Mark, Requiem, Umbral Trespass, etc). My usual last item as being able to dive into their team, deal damage, then stasis is a great way to stay alive while your team cleans up the mess you made of the enemy.

Ionian Boots of Lucidity make for a nice default, but if the enemy is running enough of a single damage type or has plenty of crowd control then buy either Mercury's Treads or Ninja Tabi instead. Boots of Swiftness are also a decent consideration if you find yourself against many enemies with slows but little hard CC ( Ashe, Nasus, Teemo, Thresh, etc).

If you are facing a ton of physical damage on the opposing team then consider this item 5th or 6th as it is the most beneficial of the armor items for this build as it allows for even faster horsing with some added damage and a slow.

I prefer this item over Bloodthirster but both work equally well as Devastating Charge's damage not only scales with critical strikes but lifesteal as well. If you need a bit of extra survivability and damage then take this or Bloodthirster last item.

Only ever buy 5th or 6th as Stormrazor and Rapid Firecannon are necessary to make this item worth buying and Stalker's Blade - Warrior and Boots are obviously standard early purchases for jungle. Highly recommended purchase most games but in certain situations (when primarily against squishy enemies) you can consider not picking it up for another important tech item.

If your enemy is stacking tons of armor then buy Lord Dominik's Regards. If they have an annoying Dr. Mundo, Volibear, Vladimir, or some awful support healer ( Soraka) then buy Mortal Reminder instead.

Against a large amount of magic damage or a fed Veigar? Then pick this up in combination with Nullifying Orb to laugh off that Primordial Burst or Unleashed Power.

Similar situation to Maw of Malmortius but more tech'd against teams with heavy crowd control options such as Veigar's Event Horizon, Lulu's Whimsy, or Warwick's Infinite Duress. If bought then Death's Dance or Bloodthirster becomes unnecessary as Mercurial Scimitar will give you your much needed lifesteal.

The jankiest of items on melee champions, generally terrible but in the right build completely and utterly broken. Buy after Stormrazor to enhance your critical damage on Stormrazor's passive and to transform your hops into leaps rivaling the ranges of enemy marksmen.

A must for this build for its cheap early attack damage and 10% CDR.

If you want more critical strike chance late game to take your 60% to 100% after buying Rapid Firecannon and Infinity Edge, then this is the best of the other three Zeal items due to its burst damage. However be aware that it makes Stormrazor's passive redundant, so selling Stormrazor afterwards in exchange for a Death's Dance or Lord Dominik's Regards is a good idea to prevent your items from becoming obsolete.

Despite the nerfs in patch 8.17 this is still an insane item beating out Duskblade of Draktharr's +100 damage and 55 AD with +235 damage and +60 AD for -100 gold at level 11. Make sure to purchase Rapid Firecannon immediately after Stormrazor to get the additional +60% damage. The reason for the insane damage Stormrazor gives is due to the fact that Devastating Charge synergizes with critical strike making a level 5 Devastating Charge (at level 13) that normally does +370 base damage with an additional +100% bAD deal double that damage instead. That means with Rapid Firecannon and Stalker's Blade - Warrior you deal 740 damage, plus double your bAD, and +65 damage from Rapid Firecannon. With just 3 items that translates to 1,360 pre-mitigation damage on Just. Your. Basic. Attack. At level 13! That's enough damage to make any enemy ADC (ノ ゜Д゜)ノ ︵ ┻━┻ .

One of my favorite items, especially on standard tank/fighter Hecarim, but it just doesn't make the cut for this build most games. Too many items are essential for this build: Stormrazor, Rapid Firecannon, Boots, Infinity Edge, and Stalker's Blade - Warrior that you are often only left with a single tech slot late game. Due to our insanely high scaling burst (]510% AD], bonus AD becomes extremely valuable due to how well it scales into our damage and so Trinity Force loses its major advantage it has over other physical fighter items: its high scaling off of base attack damage.

Unicorn Surprise:

Ghost(optional)+ Devastating Charge+ Onslaught of Shadows+ Spirit of Dread+ Rampage+ Hextech Gunblade+ Stalker's Blade
Use Devastating Charge while in fog of war to gain the element of surprise and combo it with Onslaught of Shadows to hop over a wall and onto an enemy carry. Make sure to position yourself in such a way that your Devastating Charge will push you away from the enemy team or their turrets. This is a standard hit and run combo, aiming to instantly kill an enemy then disappear to reengage a 5v4 team fight. If you have enough power you can even forsake using Onslaught of Shadows and instead save it to immediately start the team fight or use it to escape. This combo is why I prefer taking Ghost over Flash as it actually helps far more for engaging and disengaging these hit and runs than Flash is, despite the fact that this is an assassin build. A nice thing to note is that the movement speed bonus from Devastating Charge and the subsequent damage bonus from Celerity and Warpath persist for about half a second after contact is made with an enemy. So you can use Rampage immediately after you hit an enemy and it will still do full damage rather than having to time it right before contact.

Preparing the Jump:

Stalker's Blade/ Hextech Gunblade+ Devastating Charge
Using Stalker's Blade or Hextech Gunblade's slow before engaging an enemy is a good way to quickly get behind them to set up a knock back into your team. It also helps to save your Onslaught of Shadows for later use in case your target uses Flash, gaining both a kill and summoner spell advantage. This 'combo' is primarily used at early levels when ganking before level 6, but is still important and can be used mid and late game as well.

Waterwalking and Ganking:

Since The Ultimate Hat has gone away Waterwalking is my new preference to take along with Celerity or Transcendence for AP jungle builds, and if you have ever experimented with this rune on a jungler then you know exactly why. For those of you who haven't however, the movement speed this item provides is vastly underrated for ganking as the movement speed bonus stays, decaying over a second after leaving the river allowing you to keep your momentum when ganking. Level 3 ganks top become more consistent, surprise ganking bot lane and speeding past their wards is much easier, and camping mid lane becomes a breeze. The real kicker from this rune though comes indirectly from the buffs to Scuttle Crab which have given it significantly more gold and exp which in turn have been taken away from other sources in the jungle. Contesting Scuttle with Waterwalking insures you will either slaughter the enemy jungler or escape with little repercussion making the early fight much more inticing. So when taking Waterwalking almost always go for the opposite Scuttle Crab after finishing your first buff and contest all of the early Crabs for the huge lead in gold and exp.

I have found that players, those new to jungle especially, need educating on the differences between Electrocute and Predator and why and when each should be used. Firstly both keystones have the exact same base and scaling damage, making the only differences their cooldowns and Predator's movement speed, so let's go over how worth that movement speed really is. Prepare for math and a lecture on why NOT to take Predator on Hecarim.

Using above mentioned Example Build and Rune Page:
Electrocute: 810 total ms, 465 additional ms, +140 AD, +47 AP
Predator: 983 total ms, 638 additional ms, +191 AD, +64 AP
That means +51 additional AD and +17 additional AP from Predator than Electrocute when at top speed. With 310% bAD and 235% AP scaling burst that means 198 damage. That's some pretty good damage right? Except that it can only be used a fifth as often as Electrocute which on an assassin build that goes for snowballing and controlling the early and mid game, not having that additional damage consistently will vastly hurt your ability to put pressure on the map. Electrocute does 355 damage every 20 seconds while Predator does 553 damage every 100 seconds, just procing Electrocute twice as often as Predator sees an increase in average damage output. "But that's on AP Hecarim which has 200% less bAD scaling and doesn't gain the 6% AD from Celerity which factors into his burst at 510% for 183.6% scaling damage off of movement speed instead of 10% AP at 235% for only 116.5% scaling damage!" I hear you retort.

Well here you go using above mentioned Example Build and Rune Page for AD Hecarim:
Electrocute: 747 total ms, 402 additional ms, +145 AD
Predator: 901 total ms, 556 additional ms, +200 AD
+55 AD with 510% bAD scaling burst means 281 extra damage. Which once again that means either 335 damage every 20 seconds with Electrocute or 616 damage every 100 seconds with Predator. Now this is a slightly better arrangement as now Predator isn't 3.2x as worse as Electrocute, now it's only 2.7x as bad. Now you could go Ingenious Hunter of course so that you can activate Predator 67% more often, but then you are forced to forfeit Ravenous Hunter's healing or Relentless Hunter's movement speed which itself is +30 AD. But even in that situation you still only deal 616 damage every 60 seconds as opposed to 344 every 20 seconds, still 2.8x worse. Which also isn't including the 117 bonus burst damage gained from the 48 movement speed being translated into bAD and then applied to your 510% bAD scaling burst buuuuut I'm sure you get the point by now, the damage on Predator is worse for any assassin build as Electrocute takes precedence for its consistency.

But you already knew that, the whole reason you take Predator is for the movement speed of course. Well for all who think that the movement speed of Ghost combined with the damage of Electrocute is busted, think again and let me direct you to Einstein and relativity. Purely on paper Predator appears insane: it gives even more movement speed than Ghost, for an even longer duration, at nearly a third the cooldown, and it has the built in damage of Electrocute to boot. Except the movement speed, besides it's use for Warpath and Celerity's scaling, is useless. On a standard burst mage with high damage, low mobility, and possibly some CC ( Ahri, Annie, Malzahar, Morgana, Ryze,Urf, Veigar, Vladimir, etc) movement speed is a blessing. These are champions with 330-340 base movement speed whose standard builds only allow for boots, as such they cap out around 380. With no other means of movement any fighter or melee assassin can and will outrun them, meaning the only ways for them to engage teamfights is either with Flash, flanking the enemy, or sitting in a bush hoping for the enemy to be bronze. Predator is pretty insane on these champions as it now allows them to gain 125 movement speed, topping off at 505, making first strike on the enemy team a real possibility. For reference on this number a Master Yi with Berserker's Greaves and Highlander active moves at 520. 505 movement speed for 15 seconds will easily allow you to catch up to and take out 90% of enemies. This is why so many mid lane mages take either Ghost/ Flash with Electrocute or Ignite/ Flash with Predator: it gives them both early game burst to win lane and snowball mid game, and also allows them to engage teamfights and carry late game without having to fully rely on their teammates who may or may not have down syndrome.

Hecarim on the other hand already moves at a staggering 810. 800 and freaking 10. The only thing that can out run that is a Rammus with Ghost or a Quinn on crack. The movement speed is completely useless as being able to flank the enemy in 0.3 seconds instead of 0.4 seconds is a negligible difference and there are only a few champions in all of Runeterra that can out run you. This basic principle is called relativity, and is why +300 AP from Phenomenal Evil Power isn't quite as powerful as you may think when you consider the fact that Veigar already has 900 AP from items alone, making it a paltry amount of additional damage when compared to his already staggering burst. This idea is also the reason why Nasus's Siphoning Strike is pure cancer. Being a juggernaut typically building full tank items with the exception of a Trinity Force on occasion, he has laughable DPS and burst damage. However then giving him an ability that allows him to stack hundreds of additional damage on a 2.6 second cooldown is ridiculous. This is why at 550 stacks late game Nasus becomes a nigh immortal god dealing 600 damage Siphoning Strikes every 2.6 seconds, healing from Soul Eater for 200 health each hit, shredding all nearby tanks for 5% of their max hp as damage every second, all with an effective health pool of 10,500.

TL;DR

So after all of this if there is anything you take from this: if you really want more burst damage when using AD Hecarim then take Relentless Hunter and go a lifesteal item like Death's Dance or Bloodthirster to make up for your lack of health regeneration. Only if you absolutely positively have to go the fastest you possibly can or if you just can not live without the keystone should you take Predator over Electrocute on Hecarim so long as you are attempting to be an assassin, the consistency and frequency of damage vastly out ways the damage that Predator's movement speed provides.

Thank you to anyone who managed their way through this rant.
Good luck and happy killing on the Rift.