As you stated, Protection from Outsiders (spell) shouldn't apply.  Headband of Mental Prowess applies indirectly. It is already factored in via the @{wisdom_mod} portion of the DC.  So that leaves Judgment (Piercing). From what I can tell "DC" goes through some behind the scenes character sheet coding to become multiple bonuses for individual levels: @{caster#+dcbonus_level_#} (replace # with numbers).    I suggest using this for your DC: [[10+floor(@{class1_level}/2)+@{wisdom_mod}+2 + @{caster1_dcbonus_level_9}  ]]  That will take your Judgment (Piercing) into account on the DC.   Earlier you mentioned conditions, are there any conditions that need to be accounted for? Any other buffs that need to be accounted for?