Based on the cover to The Defenders #25. The cover shows Valkyrie bound upside down to a wooden stake, about to be burned by The Sons of the Serpent. The issue does show her getting knocked out, though it's quite brief. I simply wanted to show a behind the scenes look at how Valkyrie was taken to the wooden stake. One of the Serpents holds Valkyrie unconscious, while the other two prepare fire and ropes. I always found it striking how the Serpents (who are ordinary men) are able to take down the powerful Defenders.