Chosen of Markov // Markov's Servant

• WWizards of the Coast2011-01-22
  Official Ruling
  You can tap any untapped Vampire you control, including one you haven't controlled continuously since the beginning of your most recent turn, to pay the cost of Chosen of Markov's activated ability. You must have controlled Chosen of Markov continuously since the beginning of your most recent turn, however.

Rulings via Scryfall