Ambush the Valkyrie.

If she were to find herself robbed, the underworld would be unsafe for such a thief. You take position in the door's blind-spot, ready to launch a charge into the slaver.

...

The knob shakes, it creaks as the door cracks open. The joyous jeering is vibrant, the woman with her hair a frizz and her gait stumbling, closes the door sloppily.

You launch at her silently, thrusting the spear through her. It cuts cleanly through, pinning her to the wall, she looks at you, and gives an attempt at a scream, but fails. Blood drools from her mouth and pools onto the floor. Her body falls limp.