In the final, life-or-death moment, Jiang Chengxuan knew that he was no match for the embryonic Celestial Cave Heaven wielded by the Avatar of the Tree of Calamity. His decision to sacrifice his own Blessed Land, a desperate move to survive through death, allowed him to turn the tide.
In his last battle against the Avatar, Jiang Chengxuan harnessed the destructive power unleashed from the sacrifice of his Blessed Land, surpassing the peak power of an Earth Immortal. With this power, he broke through the Avatar's defenses and suppressed it entirely.
That was the final trump card of the Avatar. By utilizing the embryonic Celestial Cave Heaven, it had nearly drained all of its resources. When its power was suppressed by Jiang Chengxuan, the violent backlash destroyed it completely.