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.
4/18/2017 If you put any number of -1/-1 counters on more than one creature at once, Hapatra’s last ability triggers once for each of those creatures.
4/18/2017 If you put enough -1/-1 counters on Hapatra so that its toughness is 0 or less, its last ability triggers.
4/18/2017 If a creature with wither or infect deals damage to a creature, the controller of the creature with wither or infect puts that many -1/-1 counters on the second creature.