Aven Eternal (WAR)

Creature — Zombie Bird Warrior

Flying When this creature enters, amass Zombies 1. (Put a +1/+1 counter on an Army you control. It's also a Zombie. If you don't control an Army, create a 0/0 black Zombie Army creature token first.)

Niche amass enabler for blue-based token strategies, but the modest 3-mana flyer and single counter generation are easily outclassed by more efficient creature threats and amass payoffs in formats where it sees play.

War of the Spark — Common