sorry bout the lack of detail and rune screwups, ill fix those asap. As for my AS mastery and the greaves, i use them to break the 1 atk per sec margin, which i found lets me strike immediately after a combo for the auto crit kill more often than not, with no delay or anything. thats just my take on it, but i find it brutally effective.

Looking at this build I see a few things I don't like. First of all, why would you rank spear up at 4 before you have any real AD for the increased scaling? I guess I could see it situationally if you needed stronger early harass... but I wouldn't list it in your skills in that case.
Why flat mp5 glyphs over scaling ones? The scaling ones are as good at level 4... you really don't miss out on much and they're much better in the long run.
AD quints over flat ArP? I don't think the 6 AD really makes a big enough difference to give up a more useful stat... it's why I roll 11/0/19.
Zerker greaves and 4/4 Alacrity. But only 3/4 Sorcery? You're not an autoattacking champ... the biggest burst you have is completely independant of autoattacks - so I don't see why you would prioritize this over a more necessary Mres and CC reduction, and CDR.

I don't really like exhaust or IE; but at least IE gives decent bonuses and exhaust has it's uses... personal preference there I suppose.

I don't like downvoting builds really but you don't even explain the guide much. I'll check out your other build too, maybe there's something more there.