So, this phrase comes up a lot, mostly on the most annoying cards that I hate having to deal with that ruin my fun the most. I just don't get the design philosophy behind this phrase, and why it's in so many places (especially the Shrine of Lamashtu, which the game insists on reusing over and over again.)
Basically, my problem boils down to one simple fact: in every instance of this phrasing, it's applied to a damage type that is already non-combat - meaning the basic function of armour is already unusable upon it and only a very few methods of reducing the damage exists. Particularly damning are the "Mental" damage instances of this; as far as I can tell, there exist exactly four ways to reduce Mental damage to begin with - be Sajan who has chosen a role card (and the appropriate power feat), be Amiri who has chosen the Juggernaut role and has acquired two power feats (currently impossible as of the time of this posting), having a Ring of Protection, or burying/banishing an armour (already the rarest card type in the game).
I might even understand a consistent "Mental damage is unavoidable" mindset, but Pillbug Podiker has "cannot be reduced" Poison damage, so clearly this is not the idea.
Given that this damage is already so hard to avoid, what is the reasoning for further compounding it with the "cannot be reduced" phrasing? If having the damage be unavoidable is actually the idea, why burden it with a type at all? "Two points of damage that cannot be reduced" would be far less infuriating, I think.