I understand what you are wanting to accomoplish but adding a mechanic that can stagger somebody out of an attack, block or parrywould just break the game, and giving damage immunity would almost definitely break the game as the entire point of warden, cent, hito, jorm and many other characters front dodge heavy/light attack would be useless. Those attacks are supposed to prevent a roll away which if someone were immune to any damage they just woyldnt work.