Talk:Jarvan IV/@comment-213.80.99.211-20120317130825/@comment-4929329-20120317235115

You're talking about two different things: 1. ArPen: How much armor you ignore when attacking opponents 2. Armor Reduction: How much you reduce their armor by. Therefore they have 26% less armor, and your ArPen pierces 10% of that. But yes, that would be mulplicative, the difference being that your friends benefit from this armor reduction, and Flat ArPen stacks AFTER this reduction.