Talk:Magic penetration/@comment-81.214.165.133-20110915202700/@comment-2168040-20110916153245

According to the wiki, the flat reduction, (Abyssal Scepter) will apply first, making it 40 - 20 = 20, after which the flat penetration items are applied. However since magic penetration can't bring a champion below 0 magic resist, your target will have 0 magic resistance.