Welcome dear reader. I wrote this build after playing Blitzcrank for at least three month, so I think I know him quite well. For a long period of time I played him dps/crits and thought it was quite good. Then I realised he was almost useless, for he died in no time. Blitz is a special champ, so he needs a special build: the main ingredient is mana stacking. Why? Because of his passive, Manamune and Strength of Spirit. So here we go!

Skill Sequence

Passive - Mana Barrier
When Blitzcrank's life is brought below 20% health he activates Mana Barrier, creating a shield that lasts 10 seconds. The shield strength is equal to 50% of Blitzcrank's current mana and is not affected by armor or magic resistance. There is a one minute cooldown before Blitzcrank can activate this effect again.
Some sweet as hell passive that saves lives a lot of times. Keep in mind that the passive won't activate if you take a hit that brings you from 21% to 0% HP. Other than that, if the enemy team isn't doing insane damage, you can also use this to "tease" enemies into trying to gank you (when you still have a lot more "hp" left).

Q - Rocket Grab
Blitzcrank fires his right hand at a straight line to the target area. If his hand encounters an enemy unit it will stun them, deal magic damage, and pull the enemy unit to him.
Cost: 140 mana
Cooldown: 20 / 19 / 18 / 17 / 16 seconds
Magic Damage: 60 / 120 / 180 / 240 / 300 (+0.8 per ability power)
Mastering rocket grab is the key to mastering blitzcrank. If you're not good with the pulls and/or skillshots... then you may consider trying out another champion.

W - Overdrive
Blitzcrank super charges himself to gain dramatically increased movement and attack speed for 8 seconds.
Cost: 75 mana
Cooldown: 15 seconds
Movement Speed: 16 / 20 / 24 / 28 / 32 %
Attack Speed: 30 / 38 / 46 / 54 / 62 %
Once you achieve a high enough cooldown reduction, this becomes spamable and thus making you move a lot faster. There's around 1 second downtime between activations. Always good for emergency escapes and also quite good to stop enemies from running (Overdrive -> Get in Range for Rocket Grab -> Bring enemy to you)

E - Power Fist
Blitzcrank charges up his fist to make his next attack deal double his total attack damage and pop his target up in the air.
Cost: 25 mana
Cooldown: 9 / 8 / 7 / 6 / 5 seconds
A disabler. Useful for stopping annoying ultimates. Since higher levels only lower the cooldown, keeping this at level 1 should be enough.

Ultimate - Static Field
Passive: Blitzcrank causes lightning bolts to deal a small amount of magic damage to nearby enemies every 2.5 seconds.

Active : Blitzcrank can activate this ability to deal a huge amount of magic damage to nearby enemies and silence them for 0.5 seconds. This cannot target stealthed enemies. This removes the passive lightning bolts until Static Field becomes available again.
Cost: 150 mana
Cooldown: 30 seconds
Passive Magic Damage: 100 / 200 / 300 (+0.25 per ability power)
Active Magic Damage: 250 / 375 / 500 (+1.0 per ability power)
With a good cooldown reduction, the downtime on this is quite low and thus makes this skill a great farming tool for those crowded lanes with lots of minions. Also handy for disrupting team fights and to finish enemies off. The silence is short but it's also enough to interrupt most channeled skills :)


Regarding the skill sequence itself... As you can see on the build I did, the main focus should be getting Rocket grab maxed up for 2 reasons:
- It doesn't do bad damage;
- It makes you and your lane partner kill people;

Why is Overdrive maxed before Power Fist?
From personal experience, 1 level in Power Fist is usually enough to ensure that they stay quiet taking damage and to ensure interrupts of annoying skills (nunu's ultimate, etc). Getting more levels will only help you spam more and that's really only useful in mid/late game. On the laning phase, the level 1 cooldown should be enough.
Overdrive's speed boost is always good, but not as good as having a higher leveled Rocket Grab.

Your priority should be: Static Field (when available) > Rocket Grab > Overdrive > Power Fist.


Pros / Cons

Pros
+ Crowd crontrol amazing with both build
+ Even if i dont like to go in first, blitz is great at it.
+ Turrets kills
+ Good Shield, with a lots of mana, its like having a guardian angel
+ The funniest character to play ( try it with alistar )

Cons
- Hard to grab people ( wich make u a good blitz or a bad one )
- All spells cost a lot of mana, its hard to spam early game
- Farming is hard, early, mid or late game. ( not applicable with ap build )

Early Game

Simple as hell, try to have the other team close to your tower, pull them, play defensive, you are not the best early game character. lvl 4 or 5 i try to go gank another lane if it fails, back to base and grab some items to go in lane again. If u success help mid pushing the tower a bit then back.
One tip for the first gank, if mid isn't pushing much, try to flash and pull, thats gonna help u out covering the distance you need.


Mid Game

Thats the part where its important to follow your carry, he need to be feed. Go gank every lane, help people pushing their towers, in mid game your should get the first tower in each lane down. Try to do massive damage. One thing important, never forget your carry, he's the one that you should have your attention.


Late Game

Thats the part where u do less damage and you become a CC master, silence, stun and pulls are more important than anytime before. Keep your lane alive, follow you team, you should never be alone, always follow someone or make sure someone is following you.


ALL INFO WAS COPY PAST FROM OTHER GUIDES.