I'm not a professional but like to play in ways that other deem unviable. This guide is for my Tanky support Hecarim. I warn that you should state at the beginning of the game that you will support since there are people who will chastise you for it. To keep it clear as to how he is a support is I sell avirice blade later on after making a profit and having no room for items so I can ward and continue providing assist to the team. I didnt wanna leave that part for later as it is the queue main point as to why he is support in this build.

The pros:
-Fast melee support with a high survival and escape
-very amazing when speed is the main objective
-E is insane for ganks, keeping someone of team mates, and for that boost from base

Cons
-as a melee champ gets hungry for gold
-mana can be consumed fast if q isnt conserved
-as a support you don't want to take kills, this support is more of a bruiser but the carry benefits more from the kills

The Runes, the reason for my yellows and blues being armor and magic resist per level is the end game tankynes, the attack speed reds go hand in hand with that substantial attack speed that you will have with the extra damage output from sheen and infinity edge. and the gold quintessense for extra gold in support although I generally play with movement speed quints to give a chase boost. But that is left once youve become accustomed to low gold income supporting without gold runes and masteries.

The skills on Hecarim are very versatile with this build, i choose t max w first for that survivability early, E is a utility and your q i would conserve for when your actually attacking as it becomes an AOE damage with w in team fights. your ult is very important in the game so I would not use it to just kill an enemy champ, the best use is to save for those team fights that get very hairy, the fear cause by this makes it easy to single out the champ your team needs to focus and removes 1 second of very important battle time your opponent would need to win a team fight, 1 second is the whole world in a team fight. Your e and r are the queues to winning fight and feeding your carry. Take note when your movement speed gets high to use your E smart, run past the enemy champ and push them towards your team mates. having phage makes it impossible for them to run away. Unless your gangplank or new evelynn.

as you see, I go for a full tank with the ups on the speed buffs in utility and defense, as that boost will be your queue to ganks, damage, and escape. not much to say than that makes you into the bruiser support that nobody would expect.

Yes, to the main play. I know that I may be bland and vague on explanations, but that is because this play on Hecarim is very versatile depending on the enemy and player using hecarim.
so the start with the fairy charm and 2 of each item is the basis of most supports, some health regen that mana you need incase you go oom, and 2 wards for those gank preventions. but from the strat rushing philosophors stone is a must, the mana and health regenwill keep you in lane longer, going in hand with your W's heal, and rushing avirice blade with boots of swiftness will quickly produce that long term gold need for the whole game. now you ask, why boots of swiftness. Well hecarim scales of speed, maybe not much but substantially, which is the key to your main source of damage output, now you see I choose phage, because as you build your armor and magic res, phage will be that one item that keeps the enemy from getting away fast enoough while still maintaining that tankyness while your carry guns them down. Frozen Heart is my favorite of all armor items, It keeps you from going too OOM (out of Mana) and the DPS slow gives you a greater feel of tankyness apart from having a great amount of armor in it. now for force of nature, this is where the fun starts, that magic resistance with the speed that makes you a running monster and heal per second, is just amazing, apart from having a great heal from W. now that the tankyness is made, the reason for finishing trinity, Yomu and Shurelyas last is because of the unpresedented late game, although I would most times remove the avirice blade late to make room for more wards, but its no matter as to having shurelyas and trinity along with FoN and BoS gives you a speed boost that rivals and even surpasses teemos with E. You also may notice that almost all thesae items come from the movement speed section of the items, wink wink, passive.

So this isnt my main point, since relying on your summoner spells all the time becomes a burden to your game, but the ups of ghost is the escape and chase with the damage it gives you from your passive, i do believe speed is the queue to hecarim, while heal is that last resort item for getting away and keeping your team mates alive in those rough spots, with the way this hecarim runs, its almost like your an ambulance, to bad he doesnt heal like soraka. alternatives can be Teleport to gank places that you ward mid and late game, and flash to pull of some tricky e pushes. There is no relative cons from some of the other spells but its pretty clear as to why some of those spells arent too viable.

Well, I may not be the best at explaining this build or making a guide, Im new to this but ill try to summarize the queue playstyle of support hecarim.
1. rush avirice and philosopher for the gold you need without farm.
2.early phage and tanky items with boots of swiftness makes you a very annoying slow machine.
3. warding and slowing enemys who focus the carries is the main role of this beefy race car.
4. Don't rely on your spells, use them as last resorts, and you will see decision improvements.
5. Speed is damage. (boots of swiftness is not the greatest but does make chase easy)
Sorry for being vague but this is my first guide. i will try to improve my skills in explaining.