Belron's Demonic energy had limits.
Because of how much it surpassed Caius's magic, it could tear through any of his spells with ease. The Fiend could even disrupt the equilibrium of Caius's burrowed power to unravel them as it had done to push Caius out of the Shadow earlier.
However, this superiority hinged a lot on Caius's Magical level and while Caius was limited in how much of the Umbral Fox's energy he could harness, the Umbral Fox was still a Six-Star Beast. The equivalent of the Sixth Circle. Two Circles above Caius's Magical Level at the moment.
As such, when Caius decided to burn through his reserve of Umbral Fox energy, he broke past his usual limitation with the Trait Acquisition Potion. Which meant the Shadow hold was now at a level Belron could not so easily unravel.
