The central focus of the build is to deal damage and kill enemy champs fast, thereby resetting the cooldown on burst of speed and repeating the process. I understand where you're coming from, but I do have plans to flush out the guide to explain that end. Also just a quick little tidbit, I actually use quints of vampirism, but MOBAfire doesnt seem to have them in their banks atm.

Generally, I like this build. I'd honestly suggest finding a place for Sorcery's CDR, but that's my own personal thought there. You should also consider getting CDR runes; I think Glyphs of Focus over Shielding would be stronger in the build. The survivability is good, but faster cooldown on your Q and E is just amazing.

Other than that, if you want the Brutalizer in your build, get it earlier; the CDR will be almost worthless that late in the game. Also, consider grabbing a Frozen Mallet mid-game, probably after you've made your Black Cleaver; that slow effect is fantastic, and you can't go wrong with a little extra suvivability. To make room for that addition to the build, if you decide to go with it, I'd say sell Wriggle's Lantern after you've made your Bloodthirster.

You could an Infinity Edge in place of Youmuu's, but honestly I feel like that's a decision you'd have to make late-game. CDR and Armor Pen. vs sheer damage and crit chance/damage. All in all? This seems like a very solid build to me. With a little tweaking, it'll be ridiculous - and keep in mind, this is just my personal opinion, so feel free to throw it all out the window!