Help creating this fx!

Can someone help me breaking down how this fx is done. This work is by talented artist Songjian Cheng, I love how he created this smoky aura from this character. Would be very helpful for beginner artist like me. https://www.artstation.com/songjiancheng

(https://cdna.artstation.com/p/assets/images/images/047/904/036/original/songjian-cheng-2.gif?1648726107)

add mesh or add socket