Dragon Breath is a sacred fire attack from the dragon containing their Aura, Pressure, Stamina, Mental Force and a bit of Dragon Might to fuel it. It was never normal fire breathing but a deadly weapon that Baby Dragon can only breathe once a day.
A ball of fire condensed and shot toward Seth at breathtaking speed. Boom. The target and the place he was were incinerated and a gaping hole 50 meters deep and 20m wide was left behind.
This is how the fire dragon created his canyon and one can calculate how many days it took him to make it that big.
The dragon was weakened due to Dragon Aura Pulse, and being bound by that red liquid, constrained its power. It has to concentrate so much to manipulate the external heat and attack from the outside while also attacking from the inside to break the tiny prison.
Not to mention the red liquid was affecting its blood, somehow he can feel his blood wanting to join the red and that annoyed him.