Excellent Pawn.

The Supreme Alliance didn't want to lose their target for revenge after coming so close to it, so they tried to overwhelm the wall of dragons by crashing into it and scattering the dragons. However, each dragon is as big, durable, and powerful as their war fortress, so the Supreme Alliance had to fight tooth and nail for every inch of space that they gained. 

They were pushing the dragons, but things changed when the dragons stopped attacking the Supreme Beasts and started attacking the world in front of them. Fire poured out of their mouths in similar quantity and power as the firepower of the fortresses. The two waves of attacks clashed and created a zone of death between the two armies.

This zone was a sea of violent energy that attacked and destroyed anything that got close to it. It worked against the Supreme Beasts because they had to defend against the passive effect of the zone while advancing against the constant firepower of the dragons.