Polymorph forms should give intrinsic magic cancellation corresponding to the monster magic resistance stat of that species: 1 MC for 25+ monster MR, 2 MC for 50+ monster MR, and 3 MC for 75+ monster MR.

Make magic cancellation not work with a fixed rate versus all types of attacks it works on throughout the entire game. Instead, scale a monster’s ability to penetrate your magic cancellation based on its level, base level, maximum HP, or hit dice.

Hit dice and base level are nice if it’s desirable for all monsters of the same species to have the same MC penetration, but hit dice and maximum HP are a little weird since they aren’t meant as offensive stats. Maximum HP and actual monster level are nice because they can be discovered with a stethoscope.

Merge magic cancellation and monster magic resistance into a single stat “magical protection” which determines how easy it is for the magical portion of attacks to reach you and deal effects. All races have a low innate MP, but armor can raise it higher. Most monsters’ innate MP resembles their current monster magic resistance.

Make magic cancellation visible in the status bar.

Bump the cloak of displacement up to MC 2.

Oilskin cloaks should be MC3 instead of MC2.