nolen-b:

The disaster that resonates with Grillby’s magic is blizzard, which is actually considered a danger to his physical form as a fire elemental. This is the reason that he nearly got killed during the first resonance. Even though he was successfully revived after the incident, one of Grillby’s arms has been in an unstable and critical condition causing him to lose the control of his own flame and create unintentional damage or even cause injuries. Therefore special bandage is used to restrain such condition. However recently his condition seems to be easing up and the mutant arm occasionally changes back into its original stable form.