@Riot AP champions need to be bound to items the way AD champions are

AD champions have multiple such ways - crit items are only usable on high-damage builds, items with base AD/armor/MR scaling are much better on fighters, finally there are some melee-only (or at least melee-stronger) items.

AP champions are way more varied when it comes to playstyle - AD champions are common in 5 classes(Juggernauts, Skirmishers, Assassins, Marksmen, Divers), AP scalings are common on 8(Vanguards, Wardens, Assassins, Burst Mages, Battle Mages, Artilleries, Enchanters, Disruptors), and include more 'unique playstyle' champions like Teemo, Singed or Fiddlesticks.

Meanwhile, there are almost no ways to gate AP champions from using items not meant for them. Battle mages used to be more mana-oriented, what helped a little, but it's just getting removed, and now the only stat binding that's left is how mana regen is bound to Controllers, and how Abyssal is bound to low range.

This is not nearly enough, and this is why I think 6.9 will fail.

Let me explain this better on example:

takes way more risks than . So, he gets access to that she hasn't, and he gets more value from items like , , , and others. He deserves that, because of shorter range.

takes way more risks than . And yet, with exception of he has access to exactly the same item pool.

This is why AP items get nerfed and nerfed - when they are satisfactory buy on one champion, they are likely broken on another. A strong Zhonya's would be more than welcome and deserved for Swain, Kennen or Katarina, and would make them easier to balance, but it would likely make Lux or Xerath too safe. As a Teemo player I notice that easily - many high-elo Teemo's will buy AD items, mostly or exlusively, even though he has no direct AD scaling at all, just because they are allowed to be stronger than AP items.

And than we get to AP scaling tanks, who, as we see right now, are more than happy to use AP items like .

The only way 6.9 tries to address this is Eternity passive, but tying item's strength to amount of damage you recieve doesn't seem like really good idea, and Riot seems aware of that, as numbers on it are pretty low.

My proposition would be binding some items to AP tanks, by giving them actives that proc only on melee basic attacks, kind of like Hydras do, binding Magic Penetration to short-range mages by giving them better bases and lower scalings, and binding heavy AP items to burst mages and artilleries, by increasing their scaling - this is kind-of done now, but not nearly strong enough, almost any mage will happily buy sorcs, mask or void staff. Battle mages can be also bound by short-range, but not melee actives, and AP tanks could be bound by base-stats, i.e. item that grants you more armor the more base armor you have( or shields you for that amount, kind of like Maw does).

Some form of additional stat for heavy-damage AP champions also could be introduced as equivalent for crit strike, but that seems harder to do.

TL; DR

Riot pls do item-binding for AP champions like you do for AD champions, AD champions are bound in way that works, just copy that because why not. I get that this probably won't happen soon because we are just in "vigil night" of 6.9 and you just put a lot of work in this, but just pls consider this. You have solution ready and tested, you just need to use it.