I wouldn't buy it on Vlad. Mainly because I don't take any MPen on him, but also because as in the Rumble case I don't see any room for this item. It's definitively good on him (spam spells : check, like MS : check) but I don't see any situation it would be better than every other item. AP bruiser builds just can't afford another pure AP item.
I build him full damage lol. Sorcerers, Abyssal and Void Staff are part of it... I'd trade WotA for that with ease, more so if I use Spell Vamp quints. With 700 AP you get to almost 3k HP at level 18, I find that fairly good with his sustain.
This pathing was shown by stonewall when the changes were still on PBE. It's the same pathing that was used on season 2 if I recall correctly.