Bleeder

{3}{b}: Bleeder becomes an Enchant Creature enchantment. Attach it to a creature your
opponent controls. Place a -1/-1 counter on
enchanted creature at the beginning of each
players upkeep. If that creature dies, Bleeder
becomes a creature again.
At the beginning of your end step, if Bleeder isnt attached to a creature, you lose 2 life.