Techno-Organic Virus

Enchant target creature from a graveyard or the battlefield.
Enchanted creature gets a -1/-1 counter and is an Artifact in addition to its other types.
At the beginning of enchanted creature's controller's upkeep, put a -1/-1 counter on it.
If enchanted creature leaves play, attach Techno-Organic Virus to a new creature.
{3}: Remove a -1/-1 counter.