Coiling Passion

Coiling Passion is a drug from the novel The Langya List (introduced chapter 26 of the webnovel), the show Nirvana in Fire, and the manhua.

The Empress Dowager used it on Princess Liyang to force her to marry Xie Yu. Noble Consort Yue uses it on Commandery Princess Nihuang to try to force her to marry Sima Lei.

Adaptations
It is mentioned in episode 4 of the show.