The two spheres of Mana seemed to be at a stalemate. Thalrix had the density advantage and as much as Thessa melted the layers of his tinfoil ball away, the poor folding actually helped him.
There were so many air pockets in Thalrix's ball that the fire couldn't pass on its heat evenly and efficiently. In fact, after observing for a while, though Theron knew that Thalrix couldn't make a ball as smooth as his own, he could certainly do much better than this.
It was clear that Thalrix was a genius for a reason.
The most important point, though, was that while Thessa's Fire Mana seemed to flick away and vanish into the wind easily, from time to time, Thalrix would take control of the cooled molten Mana that flaked from his tinfoil ball and slap them back on.
Slowly, Thessa's ball of fire became smaller while Thalrix's own, while having shrunk a small bit, had remained relatively the same size.