He simply started pouring more magic into the flames, greatly increasing the intensity and turning them into a brighter shade of purple. The otherwise cold water around him quickly heated up and began to boil. Jon began sweating from the exertion as the hotter the flames, the more difficult they became to control, yet still within his capabilities. He could probably summon fiendfyre at this point but dared not to do so in the middle of the forest and without a wand to help his focus and control.