Because he had once accepted a challenge from a young heir of an Immortal Force. That was an Ancient Hero sealed away, a figure of a King, immensely powerful, and supreme over all.
But on the Martial Arts Arena, being watched by all the powerful members of that Immortal Force and many strong figures from that Great Domain, Huai ruthlessly tore the King in half in front of everyone, with no chance to fight back, killing him with a single blow.
Even though that Immortal Force went mad with rage, and many strong ones attacked Huai, he managed to fend off all of them, even going to the extent of killing the Seven Elders and slaughtering countless disciples, leaving the arena unharmed.
The master of that Immortal Force couldn't even lay a finger on Huai.
Qingyue Immortal, like a poem encapsulated in a stunning beauty, a brilliance unmatched, rivalling even Goddesses of the past.