Bab 1361: How To Bury A Star.

Every soldier be they golems, ants, zombies, and robots piled on him. His surroundings became dark because of the thickness of bodies. 

He roared in frustration. It was a mighty sound that shook the world. But he didn't roar for the sake of it. The roar was caused by a lightning spark that appeared in front of his face and exploded. It created the thunderclap of his roar. 

Lightning flashed with that explosion. It washed the world in white light and left behind nothing in its wake. The avalanche of bodies was destroyed from within and he became free again. 

This is his normal dragon breath. It is not accumulated but it is still dangerous. He is not even using cosmic force to empower his dragon breath. Just his normal dragon breath is turning the world upside down.

Unfortunately, his freedom was short-lived. The Supreme Beasts had a lot of soldiers they could sacrifice and they used them to bury him again. So he had to roar again and again.