My guess is that dragonfire is now a magical force that can transport and transform things(an advanced and upgraded version of Spike’s breath.)

This gift however it also weakened dragons, making them targets for bad guys like Opaline. If other creatures have magic then it I had to guess Yals have the power to literally move mountains and terraform lands, combine that with Flora Magic from Earth Ponies, and you have the power to change the landscape to your liking.