First, there's the Charm Divine Power of the Nine-tailed Demon Fox, enhanced by the Demonized State, plus the secondary bonus from the Four Souls Jade Fragment to the Demonized State.
Then there's the Artificial Demon Eye, which may not be particularly prestigious on its own, but can still benefit from the dual enhancements of the Demonized State and the Four Souls Jade Fragment, thus significantly improving its Effect.
And when all these BUFFs are stacked together, Momoman is completely unaware of what he's facing. Even if he were vigilant, defending against it would be quite difficult, because merely being in the sight of the Demon Eye means falling into the activated Technique Effect, which is virtually impossible to guard against.
Moreover, he was completely unaware and even looked directly into Gu Mo's eyes, naturally making the Effect of the activated Demon Eye even stronger.
