And so on training continued for about an hour with a few breaks in between of course because even after the noticeable upgrade on Stamina it would still deplete his entire Stamina if he kept a Fire Shield going. One reason behind it is that the Fire Shield naturally drains more Stamina and the second reason is that he didn't master yet, meaning he uses even more Stamina just to gain the required concentration.
Throughout the exercise, Eric noticed that Fire does indeed tamper with his raised Fire Shield, for example it doesn't give the cracking effect like everything else does. Honestly this is not at all what Eric expected, he expected to handle it swimmingly actually.
The way it interfered, it broke through the barriers and made the shield shake, well more like wiggle. This effect was mostly achieved when Mogranius was a few feet close and blasted continuously lasting Fire against Eric's shield.