Hey my name is Armin and I decided to do a support guide on Blitzcrank. I was searching for support guides all over the net but could not find anyone that I liked. Blitz is also my main champ and my main role in a team is support.
I'm here to tell you guys how to play Blitzcrank as support. If you found yourself good with Blitz you should buy a skin to him, I have a different feeling when I play with skin iBlitzcrank and piltover blitzcrank, as I said Blitz is my main and I have 2 skins so far on him I will buy the Boom Boom Blitzcrank soon...and if Riot releses some event skin like Goalkeeper Blitzcrank and so on.
In champion select you should ask your teammates if you can go support. If they say yes you should talk with your teammate that will go with you in botlane. You pick your runes and masteries and then pick Flash and Exhaust.

In the beginning Boots and one Vision Ward then you go botlane with your Adc.
Here is a fast guid where you should put the wards in botlane. You start with putting a ward at Nr.1 on the pick that will give you the vision if a jungler is going to botlane for a gank.
Lategame you should put a ward closer to dragon and Baron nashor . That will give you and your team the vision to see if the enemies is killing the Dragon or Baron then can your team come and steal the monster. I prefer Vision Ward becouse then your team can see if they have warded a place and you can remove their ward.

The whole game you have to try to stay with your Adc= attack damage carry and try to hook as many enemies as possible so your adc can get feeded and carry the game. It's very important that you let ur carry take all the kills and farm in the beginning of the game and late game u will not be able to take almost any kills becouse your adc should be fed and deals tons of damage.

It is VERY important that your adc gets as many creep kills as possible so he can earn gold and buy items before the enemies buys it. that will make your team stronger. You should just stand in the bush and wait for a hook. As you can see on the picture above you should stand in ov theese bushes. Just keep in mind that the Rocket Grab is not able to grab and enemy through their own minions. Be sure you have a clear site and just shoot your hand adn hope for the best.

I'm going to tell you how I usally do when im about to do my spells.
Everything depends on wich enemy your're playing against.
If you play against a normal adc wich can't escape easy from your hook you should wait for a hook and shoot your Rocket Grab "Q"and then Power Fist "E" and on the same time click ur Overdrive "W". Then your ulti wich is you "R" Static Field. That will silence your're enemies in a area around you. If it's needed you should put your summoner spell Exhaust on the most feeded player in the enemy team.
lets say your're playing against Ezreal that's having a spell who is almost like a flash with less cooldown. And he will use to to avoid you. When it comes to this i usally use to put my "W" Overdrive and then catch up with the enemy and then use your "E" Power Fist and then if the enemy flash you still have the Rocket Grab wich you can use to bring the enemy back to you and your team.

I use Mobility Boots to get to my lane faster and be able to catch up with my enemies.
Optional pick:
Mercury's Treads for lower cc (crowd control)
Boots of Swiftness for permament faster movement speed
Ninja Tabi when you need more tankyness

Shurelya's Battlesong
I pick it up early so me and my teammate can get to teamfights, get to our lane to defend, to chase down an enemy or to run away from an enemy. I recomend that you buy Shurelya's Battlesong but you can optionally buy Twin Shadows because it gives you as Blitzcrank speed and if you activate it, it will send out two ghosts that will give you vision and slow an enemy.

Frostfire Gauntlet
It's a good item because it fits well with my Power Fist. When I use an ability my next basic attack slows AOE. When I use my Power Fist i knock up and slow the enemy at the same time.
I would not swap this item for any other item.

Banshee's Veil
I often buy this item when the enemys have AP champions in their team. If you play against more AD champ-team then you should buy Sunfire Aegis or Randuin's Omen.

Runic Bulwark
Early-mid game you should buy Aegis of the Legion and upgrade it to Runic Bulwark. You should not replace it because it's an important support/tank item. It gives you Health, Armor and magic resist. It also got an aura that gives the allied champions armor, magic resist and health regen. This will help your AD carry to survive.

Frozen Heart
Atlast I pick a Frozen Heart it gives me armor, cooldown reduction and mana. It also got a passive that slows down enemy attack speed by 20%. Optionally you can pick an Guardian Angel

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I recommend that you fick Flash and Exhaust because the Flash to get in place for a good hook or escape.
I use Exhaust to slow or make the strongest enemy weaker.

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Ghost is optional instead of Flash. With Ghost you can run faster to escape or to catch with an enemy. Ghost also fits with Overdrive

If you are new to support or new to LoL then you can use Heal instead of Flash or Exhaust. It also heals surrounding allies.

You can use Barrier because it fits well with your passive Mana Barrier with also shields you. Double shield FTW!

This is to pick if you don't know how to save mana or spam alot. Then Clarity can restore 40% of your mana and gives mana to all surrounding allies.