It gains "When you don't control a legendary Vampire, exile this creature." Whenever Olivia attacks, return target creature card from your graveyard to the battlefield tapped and attacking
Sublime Epiphany If you like big counterspells, Sublime Epiphany has you covered, especially since you get plenty of value without even countering a spell or ability
Since you're working with many "when this creature deals damage to an opponent", you may want to place some double strike effects on them, Assault Strobe or Psychotic Fury if you're going for the early impact, which seems like you are, looking at your deck from mostly a ramp-oriented player's point of view, or high later impact cards, such as Berserkers' Onslaught, Rage Reflection or World at War.Cast Through Time could also be considered, if you're going for the constant multiple targets-hitting, or by just being a good card overall.
A Deep Dive into the Trading Card Craze For anyone who grew up with the Pokmon universe, collecting and trading cards is a connection to a world of colorful creatures and friendly battles