Hapatra, Vizier of Poisons

Whenever Hapatra, Vizier of Poisons deals
combat damage to a player, you may put a -1/-1 counter on target creature.
Whenever you put one or more -1/-1 counters on
a creature, create a 1/1 green Snake creature
token with deathtouch.
"Wait a minute! I didn't use that much poison!"