Be Blood — [s7e22] There Will

The boys track the Alpha Vampire to a hidden monastery. They attempt to negotiate, warning him that the Leviathans—his supposed allies—are actually planning to exterminate his kind by poisoning their food source.

Sam and Dean discover that the Leviathans are poisoning the human food supply with a corn syrup additive. This additive makes humans lethargic and "tasty" for Leviathans but is lethal to other monsters, such as vampires, who feed on them. [S7E22] There Will Be Blood

While the brothers are away, Bobby’s ghost continues to struggle with his mounting rage. The boys track the Alpha Vampire to a hidden monastery

His presence is marked by icy mirrors and flickering lights. such as vampires