The Plague

At the beginning of your first main phase,
add {b}{b} to your mana pool. If you use that
mana, target opponent loses 2 life. If you
don't, you lose 2 life.
At the beginning of each player's upkeep, that
player gets one death counter. If that player
doesn't control any creature, that player
gets two death counters instead. If a player
has ten or more death counters, he loses
the game.