Demon beasts were known as the hardest to deal with magic beasts, not due to their quite high average strength but due to the fact they have intelligence. The intelligence of a demon beast is rather flawed though, since they all have horribly twisted personalities that impaired their descision making and way of hunting. Magic flames leaped from the claw hands of the tree demon to the trees surrounding the open area in which the demon resided once Xavier attempted to retreat which startled him and confirmed his suspicions of the tree before him being a demon beast.
His left eye flashed for a second and a teacher-like voice appeared in his mind "The flames of a demon beasts are destructive by nature and useful for the growth of the Burning Soul Scripture that was imparted to you. Using your soul to consume them will put you on the path of inferno, an all-consuming flame." Xavier immediately knew that this voice came from his glass-eye, from the flash and familiar name of the Burning Soul Scripture. This was his next step to take, consuming the flames of magic beasts in order to further strengthen soul and temper his body but this step seemed extremely dangerous to the current Xavier as to consume flames of a beast they have to be alive and almost all fire element magic beasts, including the tree demon before him, are too powerful to contest. The insane nature of the tree demon was extremely apparent as it cackled ceaselessy as Xavier was trapped in its trap and he simply thought of him as fish on a platter.
The Burning Soul Scripture was extremely perverse, consuming to excel yourself was never seen in the Brotherhood and probably uncommon on the whole continent but what made it weirder was that it was made with so many walls that it demanded growth, immediately demanding someone fight something way more powerful than them. The Scripture had a reason to do so because reaching the first stage of three allows one to be immune of most flames, albeit some extremely strong or pure flames could hurt oneself and it just depended on the strength of the warrior using the scripture to resist some flames. The tree demon's flames couldn't hurt Xavier so he could escape but he felt as he'd be missing out on a chance to progress majorly as the tree demon certainly couldn't expect Xavier to be able to resist his flames he could get a sneak attack off but the tree demon was still extremely powerful due to its size.
Xavier's steps left footprints in the now ashy ground as he sprinted his way to the tree demon with the energy dagger in his hand, the tree demon's face became stern for a split second before continuing to laugh maniacally and once Xavier was quite a bit closer to it - it pointed it's finger towards Xavier urging the flames on it's 'leaves' to sprint towards the incoming Xavier. A mass of flames larger than himself rushed towards Xavier and he dived into it, the tree demon's laughter reached it's peak as if it was watching an ant struggle under their own weight however as Xavier's dagger made it's way through the flames with Xavier following behind it embedded itself in the trunk of the tree demon before quickly pulling out taking a chunk of meat with it.
"Gyaaaaaaaargh!" the tree demon roared with both claws on it's trunk and eyes scrunched up in pain. Xavier stared at the tree demon in awe, he hadn't expected it to be a magic beast of flesh, it appeared that the 'tree' in it's name was nothing but a facade - a way to camoflague. The 'tree' demon clawed at it's wound as it turned its gaze to Xavier, giving him a death stare with his empty eyes. The 'tree' demon's body seemed to growth looming over Xavier, it was the innate ability of all demon magic beasts 'intimidate' which allowed them to usually scare people, however Xavier could simply ignore it as his single biggest worry was gone - The body of the 'tree' demon was not made of wood and his dagger could rather easily slice through. "Graeeeeeeeyaaah!" the 'tree' demon roared once more before swiftly swinging his arm towards Xavier however he quickly rolled to the side, once the arm slammed the ground it made a small crater, scattering ash everywhere. Neither Xavier or the demon could see, however Xavier knew the 'tree' demon couldn't move or else it would've already so he decided now would be the time for his second strike. Leaping once more towards the 'tree' demon Xavier appeared from the smoke on the side he had already impaired with his first strike lunging with the dagger implanting it into the wound he'd inflicted before, ripping across the trunk of the 'tree' demon before rolling away once more.
Xavier had dealt a large blow to the demon, nearly cutting up half it's trunk leaving a fatal wound with the demon left to scream alone as he backed up and made another cloud of ash to hide. The 'tree' demon was hysterical at this point, screaming and swinging it's arms slamming the round surrounding it, and Xavier was waiting in the clouds of ash charging up an attack. Xavier had a large amount of energy as a beginner, obviously due to the fact that he was practicing the perverse Burning Soul Scripture, so he could empower his attacks with energy however this amount was far from enough to perform techniques like the ranked warriors but when he infused his dagger with enough energy it would burn like flame. Xavier flew with dagger towards the demon once again, the 'tree' demon could feel an amazing heat come towards it and it swung its arm defensively. The dagger severed the demon by the trunk from it's roots and the flames cauterized the wound leaving it powerless on the ground however the last desperate attack clipped Xavier's leg slightly impairing his movement until he healed it up.