Board Thread:Game discussion/@comment-4726614-20130404050044/@comment-4726614-20140330033826

Remember that this was tested on S3, so what follow might be incorrect.

Here is a copy of what I posted on reddit a month ago to explain the idea behind what is discussed here. Note that this is directed toward those that only want to grasp the concept and aren't interested much in the numbers.

''Armor is somewhat like an onion: The inner layers represent the base armor, while the outer ones represent the bonus armor (Not accounting Courage's passive.) If I want you to reduce the onion by 25% in size, you can do it with two way.'' I hope that onion isn't something you distaste.
 * Either by cutting directly the oinion to remove a quarter of it. you still have a part of the outer layers, and so you can still get something from the bonus armor (MR). That's how worked the masteries in season 3, I haven't tested in season 2014.
 * Or you can remove the layers one by one, and potentially take out every outer layer. Leaving no bonus armor (MR) for Courage to work on.