After giving up on Grok, I found this option. While this result could use some refining, it's just my second try with Wan 2.7 and this starter image.

Full video result: https://files.catbox.moe/db0ob7.mp4

Prompt:

> A terrified redhead has been brutally nailed down to this wooden frame, from which she cannot escape. She is securely attached at her wrists and ankles.

Woman with chainsaw uses it to brutally cut off the redhead's legs, at the upper thigh, one leg at a time. Blood spatters as the saw cuts through flesh and bone. It only takes two seconds to cut through each leg.

Since each leg is nailed firmly to the wooden frame, as each leg falls away it pivots at the ankle as it drops to the ground.

The victim is screaming in agony, while the woman with the chainsaw is enjoying herself immensely, becoming lightly spattered with blood.

At the end of the video the victim's legs are flopped onto the ground, still attached to the wooden frame at the ankles. The victim dangles helplessly from her nailed-down wrists.