I don't think we'll ever see proper AP Fighter Itemization, so instead why don't we...

...either create a third basic damage-type, or make AP fighters more hybrid-focused. The pros/cons of either idea are:

Third damage-type

• No need to balance all champions around the new damage type or new items, just champions that they apply to. The idea follows the same logic as items that give you mana vs champions that use energy or have no resource at all.
• Champions will instead have to be re-balanced around a third defensive typing which may be more work than necessary

Hybrid-focus

• No need to add new items, merely restructure some items/champions to focus moreso on hybridization and therefor making "Hybrid" damage a truly unique damage-category.
• Items that are restructured might provide more for champions that don't necessarily need it, mainly those that have abilities featuring a scaling different than what they'd typically use. This can be "fixed" by merely lowering those numbers, though.
• A balancing nightmare considering items that work well on certain champions, including crit interactions if necessary. Imagine if Diana had AD scalings alongside her AP. High burst + High fighting power = [slayer-jinx-unamused] usually if you tried going hybrid Diana, you'd be sacrificing burst for sustained fighting power. If she became a hybrid champion she'd get both. Maybe this is more of a pro than a con. I'unno.

TBH this might just be a waste of thinking. It's just something that came to mind.

How do you think we can make AP Fighters something specially unique without breaking the game?