Conficker

Enchant creature
Logic Bomb {x}{b} (You may cast this face down for {3} as an Aura spell with enchant creature. Turn it
face up any time for its logic bomb cost.)
When Conficker is turned face up, put X tokens
that are copies of Conficker onto the battlefield.
If enchanted creature would be dealt damage,
put that many -1/-1 counters on it instead.