Grimm Episode 5.13 Silence of the Slams

With Monroe's (Silas Weir Mitchell) wound miraculously healed, Nick (David Giuntoli), Hank (Russell Hornsby), Wu (Reggie Lee) and Rosalee (Bree Turner) consider what they've uncovered in Germany - and agree to keep it a secret until they can understand it better. Getting back to business as usual, Nick and Hank investigate a dead man found with his face cut off. After toxicology reports show he was injected with a neurotoxin, they bring the case to Monroe and Rosalee, who identify the victim as Patrick, a Balam. Knowing the crime was Wesen-on-Wesen helps Rosalee realize they're likely dealing with a Vibora Dorada, an Aztec snakelike Wesen capable of creating skin masks from Wesen in their Woged state.

A second death, this time of a Mexican wrestler, leads Nick and Hank to Goyo, a young wrestler who recently started sporting a new mask, and Benito, his mask maker. But when Nick and Hank arrive at Benito's shop, it's already too late. The mask Benito created from Patrick's Woged face has taken over Goyo and is making him attack Benito. With his dying breath, Benito tells Nick and Hank the name of the Santeria ritual they must perform to save Goyo. Rosalee and Monroe rush over and perform the ritual successfully, separating Goyo from the Balam mask and leaving him to face the truth about his actions.