So here's what I did:Not bad, that works too, but if the player level is high enough that his HP could tank almost anything, i don't think adding a defense stat on CM will be fun.
Cause lets be honest & Realistic. Even a Marathoner or Weight Lifter cums as easily as a teenager no matter how hard he trains. Really Prefer it to be RNG. Unless the amount of HP loss from Cumming is a Set Percentage or RNG as well.
Now enemies deal an oscillating amount of CM, for example, Slimes do 5-15%. Also, now when you use items that heal your CM (like Slime Balls, or Mushrooms), you get a temporary shield that will decrease the amount of "CM damage" an enemy deals to you.