The undead army was drawing ever closer to the Chronowork. Viggo took full responsibility for allowing them to encroach upon the sacred forest. However, he felt a burning rage well up deep within him for suffering such a disgrace. So fierce was his anger that his whole body burst into a unique flame. It would not singe even a single blade of grass in the forest, yet could consume the entirety of the undead forces.
See Forest Warrior Viggo.
Viggo is of Scandinavian origin; the meaning is "Battle, War-like".