This is something that has been bothering me for a while now. Insight runes and Sorcerer's Shoes provide magic penetration. Is this a flat-rate penetration? Or is it a percentage?
9 Greater Marks of Insight provide +8.55 magic penetration. If I'm Shen, my level 2 Vorpal Blade does 95(+0.2AP). For simplicity, say I have 0AP. If I'm facing a level 3 Akali who has 54.36 magic resist (35% reduced damage), when I use Vorpal Blade on her, does it do damage based on:
- Her magic resist minus my magic penetration: (45.81 magic resist = 31% reduced damage = 65.55 damage)
- Her magic resist minus a percentage of my Vorpal damage: (54.36 magic resist - (8.55% * 95) = 46.23 magic resist = 32% reduced damage = 64.6 damage)
- Her magic resist minus a percentage of her magic resist: (54.36 * 91.45% = 49.71 magic resist = 33% reduced damage = 63.65 damage)
The reason this confuses me is that the Void Staff provides 40% magic penetration. The Archaic Knowledge mastery reads "penetrates 15% of the target's magic resistance". There doesn't seem to be any standardized wording.