Talk:Magic penetration/@comment-5486099-20120907224444

I'm new to LoL and I'm still trying to figure some of the mechanics out. Can someone please tell me if this stat would be beneficial for a melee class like Alistar? He's free this week so I've been playing him and someone had mentioned this as something to shoot for in a build for Alistar but I'm not exactly sure why. Any help in explaining this is appreciated.