Tough Skin (-40%): Sounds like a nice modifier right? Well, keep in mind, that it doesn't help ANY against blood agents and similar contact poisons. Bitten by a comodo dragon? Happy dieing. I'd definitely make sure to not rely on such a kind of defense only. Another weakness is it's flexibility. Blunt trauma get's through.
Oh, and if you plan on layering tough skin and other DR: get the tough skin as the lowest layer.
- tough skin above normal DR: subdermal plating. You do still have the weakness against blood agents, as your outer tough skin contains blood vessels -> one scratch and you are infected.
- tough skin below normal DR: imagine an alligator. As long as the scratch doesn't hit the chinks between the hard plates (which requires a to hit modifier), you are fine.
Normal DR (0%): Doesn't protect your eyes AT ALL. One mosquito bite, one arrow in the eye ... you get it, right?
Forcefield (+20%): Don't want to care about the above? Take forcefield. But please remember: it doesn't defend against anything that is NOT pure DR and requires a different advantage to defend against.
I do also require a explanation how your DR looks and works. Pablo Diablo (Jason Markowski) gives a nice example how to do this. Please do also take style into account. Do you realy want to play a fire super that looks like he has alligator skin?
There is a difference from Silverthornes game. I do NOT limit attributes to 20. BUT: ANY superhuman ability requires a power modifier. You buy IQ 20? Fine, you are the smartest human alife. You want to buy DX 25? 5 points of those 25 require a power modifier. And to make it worse: I change the % value of some of them (you'll understand the reason after the genre shift). I do allow the following power modifiers:
Elemental -10% (usually limited by the opposite element, discuss this with me please)
If you choose your power modifier, please read carefully what problems you might face. And remember again: ANY superhuman power requires a power modifier. Some do have them included automatically. Like Magery which is automatically "magical" with no reduction. Oh if you miss magical ... anyone wanting to buy a magical ability should also buy Mana Enhancer. All others will need a power modifier for the superhuman part.