Have Nishy run and jump head-first into the wall right in front of her.
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This won't fix her brains, but sometimes she'll glitch into the wall, and often fall belowground. She'll respawn on Black's side.
You can try your luck climbing on the left side too. You'll either get stuck, glitch through, or both. You can also get randomly catapulted sky-high as you jump around, and land on the side you like... Such a welll-made game
There's little point going into the swamp beside the Condom card. Wargs, hounds, Nekos, Harpies can spawn outside (1/day in front of Black's, and Harpies in the forest). You can purchase the recipes from Black.
You don't need the Warg card at all btw. H them two times near a taming spot and he's captured. A female fapet can take care of the first H, like with Goblins.