ability power 80 => 100 Magic penetration 35% => 40% New: 10% CDR New passive unique: Your ability power is limited to 400
This would aim to:
Increase the diversity of build AP and not all the time have 
+ because we need to choose between the two.
Allow to receive support AP/CC in competition 
because the meta is not done for them.
Allowing build is not only composed of Ability Power as for exemple 
or 
pretty terrible idea no offense
Well, uh.... That would just fucking suck dick. Maybe a separate item could do that, but don't gut half the ap champs for some gimmick.
This would lower build diversity because literally everyone would build both.
You could remove it and gut the MR items. Stupid 70 MR SV and BV, 15 MR aura item every team buys, oh and of course Maw and QSS. Did I mention you get 9 armor from standard runes, and 12 mr?
Fact is, the items AP champions are "balanced around" are just two mandatory items that serve as a gold sink and work around to making enough valid AP items to make a real full build on any given mage.
That would break most mages currently. I rarely see a mage go above 400 AP, and if they do, it's because of Rabadon's. It would mean mages go 4 semi-AP / utility items, and then 2 tank items...
With that being said, I'm all for it. I'd love mages to be viable.
Hell No. This would massively gut the damage of high AP mages like lux and veigar. There are too many high MR items for your BS.
