Elenda and Azor [March of the Machine Commander]

Flying, ward {2}

Whenever Elenda and Azor attacks, you may pay {X}{W}{U}{B}. If you do, draw X cards.

At the beginning of each end step, you may pay 4 life. If you do, create a number of 1/1 black Vampire Knight creature tokens with lifelink equal to the number of cards you've drawn this turn.