In this build following this set-up exactly you will be doing true damage to any AD carry and to anyone who fails to build huge MR. With all of these items you will end full build with 666 AP and you will penetrate 69 magic resist. Plus 10%. That's just badass in of itself. Generally I play against top lane bruisers as Vlad and this build will make them waste money on tons of magic resist or suffer. Your penetration makes anyone trying to stop your damage buy 2 negatron cloaks at least. And you will still be cutting through that into their base resistances.
For my runes I like to be damage oriented. Some guides tell you to have all armor Seals and maybe even Armor Quints. To me you should be healing as much as you can off your Q and your spell vamp. More damage means more healing. I go with the 3 Armor Seals just for a bit of early game resist because generally top laners are doing AD damage. The heal Seals add to my damage and scale so they keep getting better. Same with my Glyphs and Quints I go for damage off of them so my poke hurts alot. Vlad won't have a strong early game unless you sacrifice more late game damage than I'm comfortable with. So scaling runes are my thing. Patients is worth the reward. Also with this set-up your getting 666 AP, and who doesn't want that? Your MPen Marks just add to your opponents need to get MResist.
I used to run with a 9-0-21 build on Vlad. Although this helped me move around faster, level faster, and sustain a tiny bit more (3% spell vamp), and of course the awesome CDR; Seeing a champ run away with 30 health and knowing that having 21 offense would've killed them just got to me. So I switched it up and I have been happy ever since. This is a general AP carry choice maybe minus the 9 in defense. That health will help add some tanky-ness to your early game and scale into late. Plus its some added damage which is always nice. I use 3 points in armor and only 1 in MResist because I generally am going against AD melee bruisers in lane. If mid lane Vlad is your thing this build may have too much pen to be useful for you. Also getting 9 points in Utility may be the better option.
Here's where the unique part of this build comes in. I start off basic, a general Vlad build that everyone is used to. I grab my spell vamp right after boots for the sustain and then Vlad usually has a choice to make. Haunting Guise, Spirit Vasage or an item like Rylai's. I go haunting guise because I'm after a boatload of penetration. Anyone who is paying attention to your build in top lane will go ahead and buy something to combat this. So you should expect to see a resistance item soon. By getting your T2 boots right after any negatron cloak will be null and void. Your going to be cutting through that with your 49 pen and then your 10% penetration will still be affecting the other resistances they have. Now you can focus on some damage. Rylai's is usually my next choice because this adds a lot of health and ability power, and that slow is extremely useful too. Using your pool with your new T2 boots plus Rylai's makes ganking you something comical. Depending on your game though you could be entering more team fights and less laning. It is still useful for chasing down that last enemy for the Ace or running when things don't go your way. You can substitute for an early Deathcap or get a Zhonya's if your getting focused. Once you see more resistance pieces being bought grab the icing on the cake. Your abyssal. This will help out your team, especially your mid lane, in team fights since you will all be getting 20 more penetration. Finish up with your Will of the Ancients for more Spell Vamp and again a boost to your Mid Lane AP's damage and survivability. If you haven't gotten your Rabadons yet do so.
At this point you can choose to get flasks and stick with this build or sell that Haunting Guise and grab something you feel is more useful. I generally stick with the Guise unless the game goes extremely long and I have 4k gold and nothing to buy. Buying a Void staff will only be beneficial if you can calculate that with all your other pen, 49 plus 10%, you will still be leaving a couple of the enemies with over 50 resistance. If that isn't true, or your focusing the ADC and then its a cakewalk once he's gone so it wont matter you should stick with the Guise or get something else.
Q is your best friend so you max it first. W is your escape tool, its extremely OP and can even stop 2 ignite ticks so level this up for the shorter cool down. your E can make farming easier and adds to the damage of your Q so its nice to have at lvl 3 but you won't need its full power until later. Your R is of course your ultimate. Level it at 6,11,16 like most champs, other than Udyr or Karma.
Ignite is perfect for any AP champ. It ticks away while you wait for your spells so AD champs auto attacks are countered by this. Some top laners have heals, Irelia and Yorick just for example so this will help if your going for the kill and don't want them being able to heal enough for you not to get it. Ghost is great on Vlad. Chasing with Ghost is great and much more useful top where your enemies will be looking to close gaps or lengthen them. Use ghost then pool for a speedy escape if a gank comes or your low on hp.