User blog comment:Lukeatlook/Pyro's Item Overhaul 11 - The Mage Project/@comment-1330314-20150110223619

Thoughts:
 * While mana definitely needs an itemization overhaul, I don't think mana scatter is the best way to do it: the problem with mana right now is that it's just not a fun stat. Champions who are gated by mana see it as a hindrance, and as a system it's treated as a problem to solve (usually through mana regen), rather than an interesting perk to take advantage of. On items, mana is frequently just a stat that happens to be on whatever it is you're buying (especially on and its upgrades, all of which are often taken on manaless and/or full AD champions), and not something players are specifically interested in. Even when it's on items that specialize in mana and convert it to bonus stats and effects, it's valued so little that players rarely go for those items unless they have serious mana problems (or they're /). Scattering it and mana regen across items will make those stats more common, but will not necessarily do anything to improve the value of mana or make it more interesting.
 * I also agree that penetration needs a rework, and again I don't fully agree with your system: a few other users suggested changing / in the same way you're proposing here, and Riot tested it internally, only to find that restricting penetration to bonus armor was impossible to balance without it being either useless against large resistance values or a hard counter to tanks (or even both, as 50% bonus armor/magic penetration starts weak and gets really strong really fast). There was also a lot of criticism of flat penetration/reduction, which is counter-intuitive by nature (it's made to ignore your resistances, but works better on squishies, who don't focus on resistances, than on tanks, who do). Personally, I think penetration is altogether obsolete, since it was made at a time when tanky champions were too beefy to kill otherwise, but is becoming increasingly problematic as tanks and bruisers became more manageable through itemization (which is also why I don't think we need to return to Force of Nature-style supertank items). Last Whisper and Void Staff are the worst examples of this, especially since they just provide a damage amp without any gameplay (that would still apply even if the item were made more niche, since their purpose is just to passively amplify damage by countering an existing counter). Additionally, penetration is used far too often to circumvent poor damage scalings, which creates balancing issues when you want a champion to consistently deal damage within a specific ballpark of values. I think both penetration and reduction need to ultimately disappear, so that we can see exactly how good is the state of magic/physical damage and balance from there.

While overall you have a lot of awesome ideas (Wizard's Regalia and Chillwind Crowd both look amazing), I'd take itemization down a different path. Even now I'm not sure how mana could be made more interesting, but I think the success criterion of a mana itemization overhaul should be how fun it makes the stat look.