Created an account here just to comment on this build. I've played several games so far with Blitz after adopting this build, and every single game resulted in the other team surrendering at 20. There's only two changes I would make to it. Firstly, exchange Ignite for Exhaust. A Rocket Grab/Exhaust combo is devastating, not to mention the defensive potential Exhaust has. The other change would be in skill order. I typically put only one point in Rocket Grab, one in Overdrive, and then prioritize Power Fist, since having the lower CD on Power Fist is a fantastic tool for slowing enemies you've already hooked with your grab, not to mention a great source of damage.

The latter change is more of a matter of preference, but the first just makes sense, since Ignite offers little team utility, while exhaust can easily score kill after kill for your team.

Tested this build on my smurf account with masteries 3/10/0. Yes I'm level 13. I completely wrecked against level 20's. Carried and tanked my team to victory going 14-3. This build does very great things for blitz' mana shield, it's absolutely amazing. I think i might continue this build but using masteries in offense and defense vs. defense and utility. Two Thumbs up.

Oh BTW, I have no runes ofcourse.