Originally Posted by
Evolivolution
Since I already looked quite a bit into this. SFRPG isn't handeling Damage Reduction and Resistances right, as soon as you have more than one damage type. I don't want to go into too much detail since I myself don't have enough information to dicuss this propperly, yet.
First a few tips for you:
Damage of multiple types is meant to be split up into its components equally. So an Attack that deals 16 cold and slashing damage, effectively deals 8 cold and 8 slashing damage. Order does indeed not matter here (rulewise).
All of the attacks damage get's split up after all the dice have been rolled and modifiers have been added. So the strength bonus has no significant impact on this.
DR X/cold iron doesn't have anything to do with the 'cold' damage type. It's a different descriptor that is used by weapons that are made out of cold iron to overcome damage reduction. Anyway FG treats it as damage type. This causes much more problems than it fixes. I highly recommend to always use 'DR: X' without any additional descriptor until someone has a chance to look at this part of the code to, in all honesty, completly rework it.
For your examples specifically. Let's start with Skreeling 2 & 3, since they are easier.
Skreeling 2: Incomming damage 8 S, C -> 4 S, 4 C -> 4 slashing gets reduced to 0 because of the DR and 4 cold stays like it should. Result 4 damage is correct.
Skreeling 3: Incomming damage 16 S, C -> 8 S, 8 C -> 8 slashing get's reduced to 3 because of the DR and 8 cold doesn't get reduced. Result 11 damage is correct.
Skreeling 1 is a good example of where stuff went wrong. This is what I think happend, because I looked into this. I don't know this for certain.
Incomming damage 8 C, S -> 4 C, 4 S -> get's split into 4 C and 4 S, yet FG only checks the first half of the damage for reductions so 4 C doesn't get reduced like it should and 4 S isn't considdered at all. Result is 8 damage.