Back to spoilers

Swimmer in Nightmares
Creature — Nightmare Merfolk
This creature gets +3/+0 as long as there are ten or more cards in a single graveyard. This creature can't be blocked as long as you control an Ashiok planeswalker.
Ashiok's minions plumb the depths of the ocean and the psyche.
Power/Toughness:1/4
uncommon · #275 · thb
Previewed: January 9 · Spoiled by Wizards of the Coast