Spellshock and Damage Penetration question

[Twist-Chi]

How does spellshock work exactly? Here's an example to show my confusion.

You have 100 lightning damage and use it against a target with 90% lightning resistance. The target is already spellshocked. What is the damage the target will take?
A) 12 (additional damage is tacked at the end of the formula so [100 * 0.9 = 10 * 1.2 = 12])
B) 30 (damage resistance is reduced by a flat 20% so 0.9 - 0.2 = 0.7 [100 * (1 - 0.7) = 30])
C) 28 (damage resistance is reduced by 20% of its value so 0.9 * 0.8 = 0.72 [100 * (1 - 0.72) = 28])

EDIT: Can spellshock bring a target to negative resistances if the answer is B)?


I understand penetration works this way. 90% lightning resistance against 50% penetration is (0.9 * 0.5 = 0.45). So any lightning damage you deal to this target is resisted by 45%.

What happens when you get more than 100% penetration? Assuming the resistance of the target does not exceed 100%, do you get to deal extra damage or is the extra penetration useless? If the answer to my spellshock question is B) or C), is spellshock useless for the purpose of dealing extra damage with at least 100% penetration?

[RedBucket]

Spellshock does not divide their resistances, it subtracts from them. The change in their resists is shown on their character sheet. Something with 100% all resist would have 80% all resist while spellshocked. I think all resist and elemental resist are a bit weird in how they add together, so you wouldn't see 100% lightning -> 80% lightning on a spellshocked storm drake.

[HousePet]

Spellshock subtracts 20% resist all. Resist all and normal resistances are combined by multiplying their vulnerabilities together. So for your example, the answer is A.
(100%-90%)x(100%+20%) gives 12% damage done.
So spellshock can give the target negative resistance, but it don't work against 100% resistances (unless its all type).

Resistance penetration totals above 100% give no additional effect.