Surtr Steps In!
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Red Onis were surprisingly tough and mighty Demons, with ridiculously tall sizes and immense physical strength.
It wouldn't be an understatement to think of them as almost equal to the Ancient Titans in sheer size and physical power alone, although they lacked the Titan's amazing magic and divinities.
One thing that many of those that have fought Demons have noticed was that they lacked much magical powers, their Demon Magic was only the summoning of basic elements, and even then, they were often better fighting with their mighty bodies.
Nonetheless, because of this, those that exceeded at physical strength and were smart too were incredibly dangerous threats, that could easily slay the Gods of Yggdrasil.
Even Hector, Kraxka, and Larzak, these three former mortals, who have now become powerful Gods, could not match all these Red Oni themselves.
Even less when led by three Red Oni Kings!