Blitzcrank is rarely seen as a tank, yet he can be a extremely powerful if he is built right. I play Blitzcrank a lot and i play him exclusively tank, I've tried an AP build once didn't like it.

The Masteries are pretty self Explanatory, all the ones I have chosen provide the best for a Tanking Blitzcrank; The same goes for the Runes. All though the ones I have chosen to do not have the best Armour granted at Level 18, they are much more effective in the lower levels meaning that you can lane and live for longer. I like to us Ignite and Flash Ignite as it allows you to deal some damage to fleeing opponents if you cant land that last hit. Flash is extremely useful for Blitzcrank, it allows you to flee combat b4 engaging your overdrive. It also allows you to get the angel that u need to grab a hero. A decent player will notice you run to get the shot and flee to the other side, this can just go on and on. But with flash it allows you to gain the element of surprise and get the shot.

To start the game you will want to buy a Meki Pendant as it is by far the most useful item to buy for level 1,it allows you to lane and use your Rocket Grab a lot more than anything else you can get at this time. you will then want to buy a Tear of the Goddess as soon as possible. Then purchase your boots, I prefer Boots of Swiftness as it allows you to catch and grab fleeing enemies a lot easier. Depending on the enemies team I buy items accordingly, If they have an AP team then go for Force of Nature 1st, then the Frozen Heart or Thornmail. If there team consists of more melee DPS heroes then prioritize either Thornmail or Frozen Heart.I prefer Frozen heart 1st as it reduces the enemies AS meaning you'll get hit less and it grants Mana and Armour both which will help you survive.,it also reduces the Cooldown of your spells, which helps a lot. I buy Guardian Angel as my last item as it Grants the least resistance to AD or AP which is where blitzcrank's tanking abilities come from. If after Buying all the Items i will either upgrade my Tear of the Goddess to Manamune for some extra AD or by a Warmog's Armour, if health is needed still.

One reason that Blitzcrank makes a good tank is his ability to Rocket Grab a foe, by doing this you can initiate a fight by removing one of there DDs from the team and quickly destroying them with your team, while the other team come to attack you. After Rocket Grab you should then use Powerfist to stun them further, then followed by Static Field this should nearly kill most opponent in early-mid game, if not then a hit and Ignite should finish them off. In a 1 v 1 fight its best not to use Static Field as its Passive will deal more damage over the 30 second Cooldown that the spell will do.

Blitzcrank is Effective if used correctly in combination with a high base HP and Manashield he can take fair amount of damage. His skills are effective for engaging and group fights.