While biting opponents' creatures and turning them into vampires is well and good, for five mana, Olivia can gain control of any other vampire
At the very least, Id invest in a Gravecrawler, since it so easily comes back from the graveyard and can be sacrificed to Gisa over and over
While it is expensive and somewhat slow, if you can untap with it on the battlefield and a grip full of cycling cards, the game should quickly get out of hand, despite the randomness inherent in Unpredictable Cyclone
You can get codes from 3rd party stores that collect codes from players who don't need them and resell them to you
With a 5 or more expensive drop Commander you can drop on turn 4 after this, you can drop this, draw a card, and start tapping for a lot of mana
Destroy or counter that card instead, if possible