Fen Duanhun was the Clan Master of the Burning Heaven Clan. After Yun Che killed seven of Burning Heaven Clan's Sky Profound Level elders, he was afraid of the additional damage his clan would take. He tried to deescalate but Fen Juecheng forced the situation by kidnapping Yun Che's relatives.
When Yun Che came to the Burning Heaven Clan, he and Fen Moji simultaneously attacked but were easily defeated with heavy injuries. He following Fen Yijue to Bluefire City to try and save Fen Juecheng who had been kidnapped by Yun Che. After Fen Ziya was killed and Fen Yijue heavily injured, the Burning Heaven Clan was facing imminent destruction and he requested help from the Heavenly Sword Villa and Xiao Sect. He goaded Xiao Sect by implying Yun Che would also destroy them for Xiao Kuangyun's offenses. The Xiao Sect sent Xiao Wuyi but was unable to stop Yun Che and died. He died as Yun Che killed everyone in the Burning Heaven Clan.