Adaptive Armor... Meh.

I'm no more impressed with adaptive armor than i was with Runic Blessing. Lets say your up against a mostly AD Heavy team. And pick up Thornmail, Frozen Heart, Ninja Tabi, With 9 Armor from runes and 18/12/0 Masteries. 100+100+25+9+5=239 Adaptive Armor gives you a whopping 9 Magic Resist. Even if you went fully down the Defensive tree that would only net you about an extra 2 Magic Resist. Extremely small game for the Large amount of armor you'd have to purchase. About of 180 gold worth of stats for 5550g spent. Meh. For the modest armored person that picks up about 80-100 Armor, that mastery point gets you 3-4 MR.

Maybe if it went from 4% to 10% it would genuinely be worth it.