Bad news
The temperature of the burning material influences the color of a flame. Generally, the hottest flames are blue, and they become less hot as they transition to colors like yellow, orange, and red.
A blue flame is typically associated with higher temperatures. This is often seen in flames fueled by substances that burn cleanly, such as natural gas. The blue color is a result of complete combustion, where the fuel is burned efficiently, producing a higher temperature. Still, in Rain's case, it was because a lot of mana had been used to make those flames, and the crafting skills of Maxime helped as well.
"This won't last forever, so get going," Rain said. "I will cover for you now."
"The next time, you should warn me before infusing me with that kind of energy," Elisabetha said.