It was Agatha all along who had the magic spell book in her basement. But what exactly is her motive, and WandaVision's spoilers, coming from the most unlikely of sources, suggest that we, and Wanda herself, will soon find out.

The spoiler comes in the form of a new Marvel t-shirt, depicting a scene we have yet to see. This is because the moment appears to be a fitting follow-up to the end of Episode 7 of the Disney Plus series.

In that closing moment, we learn that funny neighbor Agnes (Kathryn Hahn) is actually the powerful witch Agatha Harkness (verifying fan theories on the Internet).

The image on the t-shirt depicts Agatha standing in front of the now seated Wanda (Elizabeth Olsen) in her underground lair. Agatha is no longer holding her pet rabbit, Senor Scratchy, and her smile and the position of her arms indicate that she is quite content with something. Perhaps she is explaining her grand plan to manipulate Wanda and Hex for her own (possibly evil) purposes.

Agatha's purple magic seemed to pierce Wanda's mind; in the T-shirt image, Wanda is sitting or perhaps kneeling, further indicating that she is under Agatha's control.

Something similar may have happened to Monica Rambo (Teyonah Parris) in the post-credits scene." Pietro" (Evan Peters), or whoever it was, surprised Monica when she tried to enter Agnes' underground hatch." Prying eyes pry," he said. Her eyes glowed a dark purple, unlike the blue of her earlier confrontation with Wanda.

We already know that Pietro is under Agatha's control. If Monica falls under her spell too, Westview will be in real trouble.