The Fall Damage Cancel is a glitch in Elden Ring that lets the player use a Ruptured Crystal Tear in a Flask of Wondrous Physick to prevent fall damage or a death from a deadly fall.
Tested on patch 1.04.1.
Video uploaded to Discord by SkyTheLucario.
It is also possible to perform a critical hit on an enemy near a ledge. Just initiate the critical hit from the ledge side and if done properly you will fall but take no damage during the animation.
This can also be done in multiplayer using a duelist or invader, although this isn't allowed for speedruns.