The power of the flames that could attack the dimensions beyond was the answer to Myrth's powerful explosive energy.
Through the Combat Body of the two fused Myrth, they had enough Universe Energy that could cultivate a special dimension within them.
And that fire was now breaking out. Myrth didn't have the luxury of having the power that could change the terrain and cause the dimensions beyond to be upheld within the three dimensions. Instead, Myrth created a chamber where they could summon the fire energy and cause it to explode at a very limited rate to hide her true powers.
The fire had another interesting power that could easily create a pathway to teleport from one place to another without any ripple of energy that would be detectable in the three dimensions.