Creature — Vampire Wizard

Flying
At the beginning of combat on your turn, up to one target Blood token you control becomes a 2/2 black Bat creature with flying and haste in addition to its other types.

Bloodbat Summoner

Innistrad Remastered

Blood

Flying
Whenever this creature or another nontoken creature you control dies, create a Blood token. (It's an artifact with "{1}, {T}, Discard a card, Sacrifice this token: Draw a card.")
Whenever you create a Blood token, if you control five or more Blood tokens, transform this creature.