Critical hits damaging an enemy with 0% Incoming Weapon Damage?

[MisterRADical]

Hi, is there something I'm missing? I have an enemy with a cloak that applies a perk to certain enemies to do a few different things. I always test these things by giving them high damage (10x+ Multiply) and/or 0% Incoming Weapon, Bash, Explosive, Spell, Stagger, and/or Limb damage. The damage and incoming damage were working so I know the perk is applying from the cloak, until I critically hit the enemy which then damages them somehow. I have looked through the Entry Point's and I see nothing for "Incoming Critical Damage" and always thought it worked with Mod Weapon Damage and the like. Is it under some weird name, or is there an alternative way to reduce it? I obviously don't want it to be 0% that was just for testing, but the critical damage should be less by whatever % I make it, which I was thinking like 5% or so. I have done this a lot with my mod, lowering or increasing damage with things like Mod Weapon Damage, so I know wonder if they all don't work with criticals.. greaaat.