Talk:Kayle/@comment-68.109.110.108-20120618062254/@comment-2124153-20120618162525

^ That's the point. The value of the mastery is that you can't efficiently itemize for MPen elsewhere, so it has an outsized importance for Kayle, very similar to the situation with Shyvana. It is almost always better to have MPen if you can afford the investment, as even an AD Kayle is about 50/50 physical/magical, to say nothing of an on-hit Kayle that has a higher portion of magic DPS.

BTW, the AD mastery isn't even +10% damage: it's +10% crit damage, when crit is already +100% damage to begin with. If you have a 50% crit chance and an Infinity Edge (+50% crit damage), the added +10% only boosts your total DPS by about 3%. Since it requires 4 points in the useless Deadliness mastery, it's arguable that Lethality isn't even worth it except for pure glass cannon builds.