Arthur's flames raged on, assaulting Cassius from all sides as they threatened to consume the latter's very existence. The flames were forged using Arthur's mana, and were the product of a combination of basic spells.
Being incredibly well-versed in the subject of magic, the crimson-eyed man was naturally aware of spells even the Divine Rankers had never explored. He could forge powerful spells by simply extracting the foundation from the weakest and most common spells.
His most glaring weakness was the lack of sufficient mana, but the mana stone was definitely assisting in that aspect. Although not perfect, it could still supply him with sufficient mana for at least a few spells and a lasting close-combat battle.
Cassius's forbidden ritual was definitely an increment in the difficulty of the battle, but Arthur hadn't played even half of his cards, yet.