The Thunder Dragon Howl let out a low growl, and the thunderlight all over its body instantly danced like silver snakes, darting in every direction. The Thunder Spirit Aura gathering in the silver-white horn atop its head grew stronger and stronger, exuding a force that seemed capable of destroying heaven and earth.
The enormous spiritual energy vortex seemed like boiling water, churning without end, then madly surged into the Thunder Dragon Howl's body.
The Thunder Dragon Howl kept growling low, its voice filled with resolve and pain, as if every part of its body was being washed and tempered by wondrous thunderlight and a vast sea of spiritual energy.
Lu Xuan kept his mind focused on its body the entire time. The instant he sensed anything unusual from it, he could immediately help its breakthrough or protect its safety.
Suddenly, thunderlight burst from the Thunder Dragon Howl's body, and a silver-white phantom leapt out violently.
The phantom had one foot and one horn. The instant it appeared, wind and thunder power accompanied it, and it bore seventy to eighty percent resemblance to the Azure Horn Thunder Rhinoceros in Thunder Fire Star Cave.
"It should be that drop of essence blood left behind by the Azure Horn Thunder Rhinoceros. At the moment of the Thunder Dragon Howl's breakthrough, it released the last of its residual power, thereby merging completely with the Thunder Dragon Howl and increasing the chances of its successful breakthrough."
The thought flashed through Lu Xuan's mind.
Just then, the thunder rhinoceros phantom suddenly lit up, and countless thunderbolts and spiritual power around it poured inside.
When it fell back into the Thunder Dragon Howl's body, it was instantly like a tiger given wings. The Thunder Dragon Howl, which had already seemed somewhat spent, immediately rallied in spirit and