Satyrn
First Post
Ooh...how about "Use your bonus action and spend 1 Ki to enter (insert creative name) Stance. While in this stance you have resistance to B/S/P damage. Lasts 1 minute or until you voluntarily move more than 10' in one round."
You could add something about advantage on saves to avoid forced movement. Or even just flat out say he can't be forcibly moved.