Rules: Malenia must always be able to move, uninterrupted. This includes regular, short flinches, and stance breaks that open her up for a critical hit.
This also happens to be a RL1 NG+7 hitless kill without active buffs and all the usual restrictions.
Mordrog's Posture Bar Mod was used to keep track of and avoid stance breaks:
https://www.nexusmods.com/eldenring/m...
this was meant to be visible in the video, but I didn't realise OBS didn't record it.