Frozen Orb Damage.....specifics needed

[WarBlade]

I understand that Frozen Orb (f/o) does cold dmg as well as Piercing dmg....

Err . . . Piercing Damage? AFAIK there's no such thing. There's a "Piercing" effect available from an Amazon skill and some items for missile weapon attacks (no bug comments please) and a mention about how Cold Mastery "Pierces" Cold Resistance, but no "Piercing Damage"

I suspect you've been misled by some understated mention of Cold Mastery.

Basically Orb does Cold Damage minus the target's Resistance. That damage can then be made more effective by the ability of Cold Mastery to further impact on that Resistance. Note that the Cold Mastery percentage is applied in a multiplicative sense to the Cold Resistance.

Example: Your target has 50% Cold Resistance. You use Lvl 20 Cold Mastery listed as being an 85% reduction. That's removing 85% of 50% = 7.5% net Cold Resistance.

Normally, the diminishing returns of Cold Mastery means the skill is never built that high so you can safely assume your high resistance character won't be so severely impacted by it as in the example I presented above.