As Syrlya's grabbing the wing, Strange is running towards the wyvern. He's spotted the neck wound and has a fairly good idea of what he should do now.

The knife sticks. As Syrlya shreds the muscle and bone, the wyvern lets out another yelp of pain. The wyvern moves down to chomp at Syrlya. At the same time, a plume of purple smoke (Strange, in smoke form) moves down into the creature's throat via the neck wound. Hopefully if he asphyxiates the damn thing, it'll fall down faster than just stabbing.