Olivia, Mobilized for War is a mythic Legendary Creature — Vampire Knight card from The List (PLST), collector number SOI-248. Current market price: $3.24, TCGplayer market prices via Scryfall.
Flying Whenever another creature you control enters, you may discard a card. If you do, put a +1/+1 counter on that creature, it gains haste until end of turn, and it becomes a Vampire in addition to its other types.