Ive played Madness Vampires in both Modern and Standard and would recommend looking at
Stromkirk Condemned. He's a great discard-enabler (even during your opponents turn) and boosts your army quickly in order to clock your opponent and build up pressure. From my experience you will have problems mid game if you can't rush your opponent down, so you might want to consider
Asylum Visitor and
Lord of Lineage. The latter one is a great lord and wins you the game once you transformed him. I'd also up Olivia by 1 since having her on the field on turn 3 is much more favorable than you'd might think at first. Olivia on turn 3 means enough damage to kill your opponent on turn 4. Since it's standard you can consider playing a couple of
Stromkirk Noble as well. Can't be blocked by humans is pretty handy