While more cards are bound to be confirmed over spoiler season, so far we've seen Castle Dracula (Voldaren Estate), Count Dracula (Sorin the Mirthless, which is getting another version with art by Castlevania's Ayami Kojima), Mina Harker (Thalia, Guardian of Thraben), Sisters of the Undead (Olivia, Crimson Bride), Dracula, Lord Of Blood (Voldaren Bloodcaster), and Abraham Van Helsing (Savior of Ollenbach)
If Olivia Voldaren phases out, then control over the borrowed creature is lost, because this effect ceases to exist as Olivia phases out
If left unchecked, that could kill someone (it still needs five hits), but our tendency to be a spread the love table will likely keep that from happening
But more importantly, itll let you draw a card under unfavorable conditions when opponents draw their second card, or cast a second spell, or attack you with at least two creatures
If it doesnt have any ramplike Llanowar Elves, Cultivate, or Sol Ringyou probably need to mulligan