User blog comment:CasperNox/Changes for LoL: payment, items, gameplay./@comment-4199297-20120331122222/@comment-4199297-20120402085017

http://leagueoflegends.wikia.com/wiki/Recommended_item_code

If people _can_ stack 3x percentage penetration (masteries + 2 items) they will.

You've just pushed it so that percentage penetration is about as effective against glass canons as flat penetration/reduction is...

And if you lose that tradeoff, it just leads to hard caps like for ex. for CDR and AS...