Blowfly Infestation

Enchantment

Whenever a creature dies, if it had a -1/-1 counter on it, put a -1/-1 counter on target creature.

When the giant Tollek Worldslayer fell, a corruption erupted from his corpse to carry on his name.

2008-05-01 This ability is mandatory. If you're the only player who controls any creatures when this ability triggers, you must target one of them.
2008-05-01 When Blowfly Infestation's ability resolves, it will put a single -1/-1 counter on the targeted creature. It doesn't matter how many -1/-1 counters were on the creature that went to a graveyard as long as it had at least one on it.

Card is in preconstructed decks:

mtg.wtf