Drogon, The Black Death

Flying, Haste, Dethrone
(Whenever this creature attacks the player with the
most life or tied for most life, put a +1/+1
counter on it.)
When Drogon, The Black Death enters the battlefield target player must sacrifice a
creature or is dealt 5 damage.
When Drogon, The Black Death deals combat
damage to a player, destroy target creature.