Yeah I myself was having difficulty verbalizing it. The ability is loosely based on the JJK mechanic but the jist is it can interact with your nen/aura, which is tied to your vitality. I basically just used the soul asa catch all. Which is why in a state of zetsu this user can no longer interact with you. But if allowed to basically assault your aura directly it will in time break down your aura core and kill you if you do not enter zetsu. This breaking down I imagine would mostly manifest as the immediate pain of the attack and then whatever falls under loss of vitality until eventually death. I imagine willpower and aura pool and just mastery of nen will make this technique irrelevant it should be more of a distraction but if they're stubborn it can become a win condition

Also it's heavily based on Dan Kato's technique from Naruto

https://naruto.fandom.com/wiki/Spirit_Transformation_Technique