Making an attack roll is when you roll a D20 and add your attack bonus. This will be your attack roll value. You use
Your hit roll is the attack roll you use to compare vs the dodge value.
Against Dodge,a hit roll is compared vs the dodge value. If the hit roll value is equal or higher than the dodge value. An attack is considered to have hit. If it is less, an attack is considered to have missed
If the hit roll value is 10 or higher than the dodge value. The hit would have considered to have critically hit.
Armor comes into play when an attack hits a target. You reduce the damage done by the following value:
Damage reduction = Armor - Armor Piercing Value.
Armor works against all attacks that require a attack roll.
Thus the final formula for calculating damage for an attack roll based attack is:
Original Damage Done - (Armor Value - Armor Piercing Value)
Armor Piercing is calculated by diving your attack roll by half(round down) and then adding any additional armor piercing modifiers
Attack Roll Armor Piercing = (Attack Roll/2) + Other Modifiers
Saving throw comes against certain effects. There are three types, Reflex, Fortitude and Will. All 3 follow the same mechanics.
Your saving throw roll is equal to:
D20 + Saving Throw modifier
Basic saving throw refers to saving throee with a set success or failure. You compare the saving throw roll vs the DC. If it is equal or higher than the DC, you are considered to have succeeded, if you rolled lower than the DC, you are considered to have failed.
A normal saving throw has 4 degrees of success or failure.
Critical Failure(CF): When your roll is 10 or more less than the DC
Failure(F): When your roll is less than 10 lesser than the DC
Success(S): When you roll is less than 10 more than or the DC or equal to the DC.
Critical Success(CS): When your roll is 10 or more than the DC.