Haki resist law's abilities and one of them is
Soul Manipulation but I'm not sure if haki resists all of law's abilities outverse yet... So....
if you have
Haki and the devil fruit user has soul manipulation then it's literally near impossible to affect them (Law has haki, a pretty strong one but can't at all use his devil fruit abilities on Big mom and Kaido) Aokiji has even Advanced Armament Haki (God tier)
The mind is tricky since
Observation haki can make you turn off your mind (I think) and solely use observation haki (
Instinctive Reaction,
Precog,
Enhanced Senses and
Extrasensory Perception)
link,
link and
link
How does that work?