hellhound cut healing

Annabeth drew her sword.
There on the rocks just above us was a black hound the size of a rhino, with lava-red eyes and fangs like daggers.
It was looking straight at me.
Nobody moved except Annabeth, who yelled, "Percy, run!"
She tried to step in front of me, but the hound was too fast. It leaped over her — an enormous shadow with teeth — and just as it hit me, as I stumbled backward and felt its razor-sharp claws ripping through my armor, there was a cascade of thwacking sounds, like forty pieces of paper being ripped one after the other. From the hounds neck sprouted a cluster of arrows. The monster fell dead at my feet.
By some miracle, I was still alive. I didn't want to look underneath the ruins of my shredded armor. My chest felt warm and wet, and I knew I was badly cut. Another second, and the monster would've turned me into a hundred pounds of delicatessen meat.

You're wounded," Annabeth told me. "Quick, Percy, get in the water."
"I'm okay."
"No, you're not," she said. "Chiron, watch this."
I was too tired to argue. I stepped back into the creek, the whole camp gathering around me.
Instantly, I felt better. I could feel the cuts on my chest closing up. Some of the campers gasped.


TLT pg.130