'Grimm' season 6 episode 12 spoilers: The Zerstörer arrives in Portland

Promotional poster of "Grimm" | Facebook/NBCGrimm

In episode 12 — the show's penultimate episode — Diana (Hannah R. Lloyd) will be pursued by a dark force called the Zerstörer, which is described as the greatest foe that Nick (David Giuntoli) will face so far.

In an attempt to protect her, Nick, together with Diana's parents, Adalind (Claire Coffee), and Capt. Renard (Sasha Roiz), will hide her in a cabin in the woods. Fans who have watched the show from the beginning will recognize it as the scene of Nick's first investigation as a Grimm, making the show come full circle before it ends.

However, their attempt to hide her will not work, as the trailer showed them in the cabin with Diana saying, "He's here" while looking in a mirror while holding the magic stick. The Zerstörer then breaks out into the world in the following scene.

Meanwhile, Hank (Russell Hornsby) and Wu (Reggie) will investigate a case that will also lead them to the Zerstörer. Another sequence in the trailer showed the creature at the police station, with Hank (Russell Hornsby) attempting to stop it using a semi-automatic rifle.

Eve (Elizabeth Tulloch), Monroe (Silas Weir Mitchell), and Rosalee (Bree Turner) will continue working together in the Spice Shop in order to find out more information about the mysterious stick. They will stumble upon something about the magical item's origins and something that can help them find out if the stick will be able to help them in their fight against the Zerstörer. On the other hand, what they found could also be something that would worsen the situation for them, as Giuntoli described in a TVGuide interview that "It's the worst stick in the world."

Episode 12, titled "Zerstörer Shrugged," will air on March 24, Friday, at 8 p.m. EDT on NBC. The show's series finale, meanwhile, will air on March 31.