Hello! First off I wanted to say that I absolutely love this system. I honestly love all of your stuff, but this one especially is the perfect combination of all of my favorite things in one package.
That being said, I unfortunately need clarification on one thing: what happens when you have a hindrance (whether from your own conditions or trauma, or when facing another character’s conditions like in the lamia example) and you decide to spend a light or dark die?
I don’t see it say that spending reserve dice when facing a hindrance is disallowed. However, hindrances cause you to roll for disadvantage and reserve die roll for advantage, so you can’t just swap from disadvantage to advantage because the hindrance dice would actually be improving your roll.
My house rule has been to cancel each other out 1-for-1 and whichever remains rolls for advantage or disadvantage. So you can lessen the effect of 2 hindrances with 1 reserve die, or spend 2 reserve die to get advantage after canceling out 1 hindrance, etc.
Is this assumption in line with what your intent was?