Rowan noticed the wounds all over its body were squirming as if it was attempting to heal, but a force would tear the wound open again and again, causing the Dragon to roar in pain. Rowan had experienced something similar when he fought with the General who had the ability to cut through his Constitution and slow down his healing process, but what was happening to Vraegar was a hundred times worse.
Every time the Dragon tried to heal, the wound tore open, but more violently than before, making each wound from the dragon grow progressively worse, it was as if the more vitality a creature had, the more they would get to suffer, as the healing from the dragon appears to be promoting a more extreme backlash from whatever forces was inside the wound.
Even as he watched, the back leg of the black dragon simply fell off when a particularly nasty wound in its spine spread to the limb. The roar of pain from the dragon was long, and panic filled its gaze.