Cloudpiercer is a common Creature — Dinosaur card from Magic Online Promos (PRM), collector number 80979.
Mutate {3}{R} (If you cast this spell for its mutate cost, put it over or under target non-Human creature you own. They mutate into the creature on top plus all abilities from under it.) Reach Whenever this creature mutates, you may discard a card. If you do, draw a card.