based on my observations with warmongers is very situational. if your team's tank is being hosed... grab it and you withstand the 4 second stun a team fight can have on a tank and will give your team enough time to save you or the tank. the regen is nice once you get it and it scales nice with vlad but overall if your ganking so hard i say skip it and go for the rod than the hat. if the other team starts putting up a solid fight then i would get warmongers but i just go straight ability power from the point of the hat and start shredding the enemy. i noticed that when i did this i got more kills and spent more time in team fights and eating minions for gold. at that point i already had 4k hp and had the whole team fearing my wrath

Thanks for this information!
Checkout my update to this guide based on your comment.

when i personally tried out the new 15% ability boots... my transfusion was at 1.8 sec cd and i could spam it 3 times before another Tides of Blood. the CD was rediculous and i became a hulking mass of death and dismemberment even if i ran from a fight i was gaurnteed to at least stay alive long enough to get to my base or a turret.

Magic penetration does not necessarily mean early game kills. Constant in and out attacks do - more consistent attacks proves more effective than 1 or 2 stronger hits. I've worn magic penetration boots for a long time, and when I changed to the 3+ in speed, I saw a huge difference. Speed saves Vlad and, at the same time, makes him the awesome chaser that he is.

Now, the 15% cool-down boots may also allow for consistent attacks while still protecting your ability to flee (the cool-down of pool of blood). More trials on these new boots will be done.

I myself agree with Ball...
the magic pen boots are ridiculous if you rune for magic pen, not to mention later game even if you do have that void staff

now i may be kinda "new" to vlad as i've only offically had him for 3 dayz but i've not stopped playing him and i dont think that warmongers armor is worth it after the new patch. i mean have you SEEN the new hat? 155 ap +30% of your AP thats a better scale imo for health than that chest piece, i just i unno... it may be because im all about running around nuking everything and team pushing but thats just how i see it

now like i said before i've only been playing him for a short time and in the last 3 days there have been only 4 games where i've actually been able to GET to lich bane. its like right after you get the scepter and the hat your like some kind of god burning down an entire team in 6 seconds in a team fight, ravaging them and standing triumphant over their dead bodies. might be because i played twitch alot and with him being a glass cannon and all i'm very careful with vlad so i never saw a point to have the warmongers. i just get the staff sooner than the hat and with your passive ability i still get 4k hp by lvl 18

Why are you using the 3 movement boots as opposed to the Magic Pen boots? It just seems as if the magic pen would help for the early kills to build up to the rest of this semi-expensive build. THink about it.

good build.
its called tides of blood and you up that skill the last xD lol