Unacunerra had thought in a lengthy manner about Rosemary and her particular mana trait, which was perfectly in tune with her elemental affinity, the mana she produced was already that of her element, meaning that if the skeleton mage made single mistake in the conversion of his energy, in the building of his spells, or in the casting, he would be outsped as his enemy could skip one of those steps entirely.
Most importantly about it, was when she unleashed her zone, converting the wild mana into her special trait, which while it could directly be used for her spells, was not simply an element, making it much harder to breakdown and convert into Unacunerra's earth, the undead did not possess a special trait, unlike her, unlike his king.
