Seeing a ton of Vladimir players build WRONG
Hextech / Will of agents too early.
Vlad will ALWAYS be weak, until he maxes Q. Q does not max until 7-9
He has a healing mechanic, but that does not mean he should be buying a Spirit Visage 
So what's a good first item? Boots + Potions --> giants belt into relais (Slow Q to help team prioritize targets without the need of your FLASH w) or Boots + potions --> sorc boots into lisandries torment (2% of targets hp + magic pen, this means if you cast E ONCE on the enemy team, 10-20% hp of their WHOLE team will be gone) note that vlad pool slows. . doubling the effect of lisandries torment
at this point vlad will have enough magic pen to 100-0 ANY ADC regardless of build or heavily zone them out.
THEN you buy will of agents, but I would rather prefer either hourglass or building the other starting item.
Lisandries + Relais --> hourglass / death cap / voidstaff / randoins depending on who you are fighting.
Just because vlad is fighting an assasin, does not mean you need to change your starting build.
Vlad vs Akali - the reason most vlads die to akali, is because of the enemy jungler and the first blood ends up putting him behind in levels. The main reason vlad NEVER catches back up to akali's power spike, is because he isn't strong enough to assist in teamfights or clear wave fast enough to do so.
(Rushing spirit visage = fail)
If you are struggling against akali, ask your sup or buy pink wards, not magic resist.
Vlad vs Zed - hourglass rush is perfectly fine, but the huge downside is no health to sustain the armor of hour glass, and no magic pen to 100-0 the enemy adc / junglers
Please don't make your team embarrassed for giving you the solo lane.