Belbe, Corrupted Observer

$0.39

At the start of each postcombat main phase, the active player adds {C}{C} for every opponent of yours who lost life that turn. On your turn, hitting all three opponents means six extra colorless mana in your second main phase. The catch is that it works on their turns too: an opponent who damages the others gets mana as well. The deck runs cheap evasive creatures and drain effects so every opponent loses at least 1 life, then turns that mana into colorless threats and expensive artifacts.

In the recorded games, Belbe most often used the mana to cast huge colorless cards early, like Ugin, the Ineffable, Eldrazi Ravager and Dreamstone Hedron, along with Terastodon and Tooth and Nail. Faster lists used Witherbloom Apprentice and Sanctum of Stone Fangs to drain the table, Ad Nauseam to refill, and Mikaeus, the Unhallowed with Triskelion as a finish. Chalice of the Void, Static Orb and Culling Ritual slowed down cheap artifact and enchantment decks. The weak points were real: opponents learned to aim attacks so they collected Belbe's mana themselves, and losing an early card engine like Pulse Tracker left the deck short on gas.