After breaking through the Purple Mansion Realm, the Nine Netherworld Storm ushered in that night. The Nine Netherworld Storm would center on the Sun and Moon Gate and release the terrifying Nine Netherworld cold energy toward the entire Qiankun Peak.
If you practice the Qiankun Sun and Moon Technique/Taiyi Liangyi Gong, you can reduce the invasion of Jiuyou's cold energy, but you will still be injured.
Fortunately, Xiao Mu is physically strong enough and has practiced the Qiankun Hegemon Body, so he is safe and sound!