Alistra, Vizier of Corruption

Infect (This creature deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)
Whenever one or more -1/-1 counters are put onto a target creature, create a 1/1 Black and Green Snake creature token with Infect.
Whenever one or more poison counters are put on a target opponent, create a 1/1 Green Snake creature token with Deathtouch.