Hi, i'm an BR player (Then english isn't my native language :/ ) since Season 4. I've reached level 30 at the end of the season, and recently started playing Ranked, but i'm locked in Bronze 3 (as my "great" server has a lot of trolls and AFK's :( ).
Anyway, Blitzcrank is my main support (and maybe my main champion) and i wanted to share my knowledge with you, my readers.

P.S. This is my first guide :P
And sry for any grammar errors you may see in this guide.

Blitzcrank is (in my opinion) the most versatile champion in League. Do you want to build AD? YOU CAN! Do you want to build AP? Guess what... YOU CAN! Do you want to make a support build? YOU CAN! Do you want to play jungle with with him? It's unbelivable but... YOU CAN!

And Blitz has one of the most annoying skills. The Rocket Grab of DOOM!

Enough talking about what we can or not do. Let´s go to the guide.

Pros +You have 3 CC skills. +AOE Silence. +Rocket grab of DOOM. +Speed Buff (Either for Escape or Chase). +Kinda low CD.

Cons -Mana Hungry -Team Dependent -A bit hard to master the grab Invisible text! Invisible text! Invisible text!

• Greater Quintessence of Health: This gives you more sustain in early game.
  
• greater mark of hybrid penetration: You deal both physical and magic damage then... its self explanatory, right?
  
• Greater Glyph of Magic Resist: You need some defense in early game (against Support).
  
• Greater Seal of Armor: You need defense in early game (against ADC)

• are to weaken enemy pokes in early. is when you need mana quick and you have no mana potions. And is self explanatory.
  and are good for earning much life in early game (maybe late too...) is self explanatory too.

• Your must be maxed out first than others (CDR and Scale Damage).
• Your second skill priority is (Scale Speed).
• The last skill you should max is (This one doesn't scale damage, up this skill will only give CDR).

Skill Priority: Static Field > Rocket Grab > Overdrive > Power Fist

Let's go to the moment you're waiting for!

Introduction

The build i'll show is focused in:

• Be Tanky (Like a )
• Build 40% CDR(Low CD like a )
• Be as fast as using (Maybe more fast!)

Champion Select

Yes, my build starts in the champion selection, because there's 2 builds you can use, and you'll choose which them is the best for the game.

As you know there's 2 items which gives you gold passively: face of the mountain and talisman of ascension; each one has your pros and cons.

face of the mountain Pros: +Gives you 10% CDR +Gives an "offensive shield" to an ally +Gives gold to you and to the nearest ally.

Cons: -Limited uses of the gold passive -Your 1st recipe item doesn't have any regeneration buff.

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talisman of ascension Pros: +Gives you 10% CDR +Unlimited uses of your gold passive. +Gives speed buff for your team (As an active, of course) +Gives you extra mana regen in all recipe items.(health regen too, in the 2nd recipe item )

Cons: -Gives you less gold than face of the mountain. -You can't "share" its gold with an ally. -You won't be able to create a shield to aid an ally. -You will take more time to complete your build.

As you can see, you have to choose wisely your item, because it'll change your whole game.

When to build talisman of ascension:
-When your lane rivals are a big threat for you and your ADC, because the items you'll use to build it has Mana Regen --> Mana and Health regen , as you're Mana Hungry, it'll give you more sustain in lane (More Mana regen = more Rocket Grab. More Rocket Grab = More kills. More kills = ADC feeded. ADC feeded = GG)

When to build face of the mountain:

When your lane rivals aren't a big threat for you and your ADC (Weak CC enemies), because your ADC will farm more easily (ADC farm = Face of the montain's passive. Face of the montain's passive = More Gold for you and your ADC. More Gold for you and your ADC = Early build completion. Early build completion = GG.)

Early Game

When the game starts, always buy: Your "Gold Passive" item, a , a , a and a .

Focus in buy the first, because you need vision of the "border" of your lane to avoid ganks.

In your first back (or second), if you already bought , start building your .

When you finish building it, upgrade your "Gold Passive" item and/or start building your boots.

Mid/Late Game

Later, start building your (SLOW EVERYWHERE).

When you finish it, make your last upgrade in your "Gold Passive" item and start building your last core item (your situational one).

Situation Item

Well, in this part of the build you have to see what enemy champion is feeded (or has more "power"). If an AD champion is strong, buy a or a . If an AP champion is strong, buy (For coletive Magic Resist) or (Against REALlY strong AP champions, to absorb its damage).

You can sell your to build another item, but you'll need your team's help to ward the map.

Well, with one more slot you can build another situational item or build a (For eneny slowness).

Well, this is my build, it's still in development.
Thanks for reading, and please leave your feedback.
Soon, i'll bring an explanation of the Blitzcrank's skills and about the matchups against some ADCs and Supports.