ad or armor pen runes

[quote=luizdeh]Mitigation is 100/(100+armor). You then multiply your damage by that number. Say you do 200 damage, enemy has 100 armor. You now do 100 damage (multiplier is 0.5). With 10 armor pen, it goes up to ~105 damage. There is a point where Armor Pen > flat AD. Don't remember when, but it's far enough into the game that you should just get that 8% armor pen from masteries plus [[last whisper]] and just go to town.[/quote]