Something snapped inside Luke when he pierced the head of the subsequent Red Fang. His mind had gone blank due to the pain, so when he pulled his sword, he pulled it upward, even though he had to destroy another part of the monster's skull. Still, he did so with ease…
After the monster died, he attacked the next one. Instead of using Stinger, he just ran toward it and swung his sword toward the eyes of the creature, and blinded it. Once he did that, he grabbed the upper jaw of the beast and forcefully opened it before making his sword pierce the interior until it reached the brain.
