This on one hand was due to Zhang Yu's continuous honing of his physical defense from the Qi Refinement stage until now, always resisting the damage inflicted by Life Flame on his body.
On the other hand, Zhang Yu secretly utilized the "Blood Tide Essence Qi Holy Observation" to transform various muscles and organs in his body into flames, better countering the Life Flame.
Moreover, during each of his disappearances and appearances, a clone would replace him, emerging from the Immortal Cave Heaven to battle against Ying Aikun.
Whenever a clone was somewhat heavily injured, it would retreat into the Immortal Cave Heaven to heal.
At this moment, Zhang Yu was not fighting Ying Aikun alone, but was controlling over thirty clones, rotating between healing and fighting, colliding with Ying Aikun in turn through the power of Cave Heaven Manifestation.
