this build is about playing blitzcrank as a suport early game and a nice tank mid to early game
it is important to understand that u play blitz to help your team get fed and play a role as a tank to ranged champs such as ashe, vayne etc so your team can get the feed it needs

early game blitz has a huge mana issue that is why i prefer getting him a dorans ring for the HP,mana regeneration, and AP u need to spam your Q but not waste it so you can grab enemys to get the kills for you and your team mates. i chose heal as a summoner spell because when u are low in HP u can use it to lure your oponents near the tower to land a good combo with your Q(grab) and E(stun) so he will take several hits from the tower.In this part of the game you need to farm so u can get tear of the godness and your boots

mid game blitz starts to go more and more tanky so u can now start fights without any problem just pull someone from enemy team or walk right in them so u can keep your grab for those champs who escape with 100 or less HP. at this part of the game u need to have at least manamune boots and frozen heart.dont forget u are a "support" tank u play to help your team so dont ty to steal kills with your R

late game blitz is the tank u need to endure all the heave enemy damage and CC efects he can also cut off enemy ultis like katarina's death lotus or nunu's absolute zero with his own ulti. dont forget that u must start all the fights either with your Q or by going in your enemy team. also you can tank enemy towers easily!

blitz pros is that he is a good suporter tank he can deal decent damage he has a lot of HP on his own so u dont need many HP items and is a great help in lanes also great movement speed
his cons are that he cant deal as much damage on his own, you cant do anything at all if you are in a noob team, he is not so tanky early game so care