Riot's Vault

{t}: Add {w/b} to your mana pool.

At the beginning of your upkeep, if you control
Agony's Vault, Lasher's Vault, Phage's Vault,
and Riot's Vault, exile them and create Hybrid,
a legendary 12/12 colorless Symbiote creature
with Menace, Trample, Haste, and Lifelink
and "When this creature dies, create four 3/3 colorless Symbiote creature tokens"

They're becoming some kind of Hybrid! - Zwerling