Vraska, Swarm's Eminence [War of the Spark Prerelease Promos]

Cost: 2 B/G B/G Whenever a creature you control with deathtouch deals damage to a player or planeswalker, put a 1/ 1 counter on that creature.
−2: Create a 1/1 black Assassin creature token with deathtouch and "Whenever this creature deals damage to a planeswalker, destroy that planeswalker."