Set all your graphical settings to low to ensure a steady 60 FPS because otherwise the glitch won't work.

Position yourself here

This is a relatively new glitch so not much is known about it. But after two hours of practicing, I'll try my best to explain it.

First, you'll need a shield and a keyboard since this won't work with a controller.
Hold the right mouse button to block and ALT at the same time. After two or so seconds, you'll press
W and because it's so precise, you'll likely need a metronome to make it work.
For some reason, making your character overencumbered seems to make the glitch easier to pull off. If done right, you'll zip straight up the rise where the host will be hiding.

I personally used this metronome program and set the BPM to 109 with the fourth beat being the indicator to press W
https://www.nch.com.au/metronome/index.html
or

An example of it in action.