Testing Blitz now with success, here is why :

1/ Blitz is firstly a tank. You can play Blitz the hard way and focus on killing (even with this build) but your teammates expect you to tank partly or mainly. I can win games being the only tank with that stuff (4600 HP at end games + HP Regen + Passive Mana Barrier).

2/ Then comes the whole package : Ability Power, Health, HP regen, Armor, Movement Speed, you name it, you got it. Runes & Masteries have got MP regen, MP total, Speed and Magic Penetration.

3/ Main idea is to take advantage of Ability Power with Grab (+80% AP) and Ulti (+100% AP) plus Lich Passive (+100% AP). And 1 point in Ignite mastery gives you +10 AP all game. And Exhaust spell(*) is there to help you Rocket Grab this son of a b**** that has been harassing you, with the potential support of your teammates' DPS.
(*) 1 mastery point in Exhaust spell will bring the **** out of him (lower armor and magic resist).

4/ And 1 item to earn Gold !!! Blitz isn't quite a farmer, so gold incomes are much appreciated. This build doesn't require or show many expensive items whom Blitz could never offer anyway. Only 14k gold necessary for this whole stuff !! And if game is lasting long because of weak teammates, you can evolve Heart of Gold into pretty strong stuff to tank even more.

5/ Finally, this build gives a good stack of MP which supports Mana Barrier passive Ability.

I don't think i have forgotten anything about Blitz and its capabilities : Tank HP, Instant Offense in AP damage, MP regen to support 4 skills constantly activated, and gold market revenues.

Build finally finished. I will give a thought about CD reduction Runes instead of MP regen, or mixing the two of them.
I am Blitzcrank, i am a Tank and i can Blitz ! 80% stats of won games with this, and i am an easy dude on the mouse clicks. :D
Please feel free to comment.