Acolyte of Chayula-Darkness bug?

The description for "darkness" is "Damage taken is reserved from darkness before being taken from life or energy shield". If I understand it correctly, life or es should not be reduced as long as there is still unreserved darkness. However, it's consistantly deducting es/hp while darkness is not fully reserved espeically when it's poison damage or fire ring. Beeding might do the same but I am not sure. This seems to be a bug to me and I am surprised that I can't find any relevent thread reporting this. This needs to be fixe so this ascendancy is playable.