As one of the most powerful Divine Beasts of the ancient times, Nox's strength was considered unique among the Divine Beasts of the Ryuzakinus Continent, on par with the Amethyst Behemoth. Even Zi's ancestors had perished at the hands of Nox, which attests to its formidable power.
By a twist of fate, Ye Yinzhu had sealed Nox within his own Desolate Dragon Yin's Zither, using the Essence of Dragon Soul Wood for the body, important components of the Giant Divine Dragon's bones, teeth, and horns for the zither's structure, tendons from the Seven Dragon Kings for the strings, and the addition of Nox's spirit, had created this Super Divine Artefact.