Some AP Itemization Ideas
Since Riot seems to be adding a lot of new items recently, I couldn't help but hope that they were planning on adding a couple new AP items next to remedy the poor item rework we just got.
First off, I think the best way to fix this auto push the wave meta is to replace last chapter's passive that increases mana by 20% on level up with one that refunds mana when hitting enemy champions instead, so if you just spam the wave none stop you'll run out of mana a lot faster than someone who's actually trying to fight. I also think tear could be buffed for none spammy champs, so they can build it. I saw a post mention having tear stacks be based on a percentage of mana used rather than abilities used. Hextech GLP needs more of an identity because protobelt is better for catching than glp is, in my opinion. Maybe it should be slimmer and much more like a skillshot, but gain range and slow harder in return.
New Items:
AP Assassins
**Speed Based Item ** Stats: AP Movement Speed Magic Penetration Active: For the next 2 seconds, gain AP based on how much distance you travel, the additional AP lasting for 2 seconds afterwards. Would count all forms of blinks, dashes, etc. AP assassins are all very mobile, so a passive like this would favor them over mages.
**Sustain Item ** Stats: AP Health Passive: After dealing a certain amount of damage to an enemy champion, Heal for 35% of that damage dealt over 3 seconds. A quality item for team fighting to keep from getting blown up instantly, and the reason I didn't choose a shield is because this can be countered by Grevious Wounds unlike a shield, so it would be less OP; but a shield could work just as well. This could also be useful for close ranged mages like Annie as well.
**Enabling Item ** Stats: AP Movement Speed Magic Penetration Passive: After becoming untargettable, gain 50% tenacity for 1.5 seconds. Would synergize well with zhonyas, but I can see champs like Akali (shroud), EKko (ult), etc. using it regardless, making it harder to lock them down directly after becoming vulnerable again.
Now we can separate AP assassins from mages with items that make them better in the thick of a battle, as well as more mobility centered.
Mages
In general I would like to have 2 items to go along with Rabadon's, they'd all build out of a little rabadon's cap that increases ap by 20%. The other two options won't simply bump that up to 40% though, they'd have a more niche role. Leaving Rabadons as the consistent AP choice for champs that need to do as much damage as possible with every ability hit like Poke mages.
Combo Mage Item Stats: 120 AP Passive: Increase AP by 20%. (From the small Rabadon's cap passive) Passive: Upon hitting an enemy champion with a snare, stun, fear, charm, or sleep cc ability, gain a burst of magic penetration lasting till 0.5 seconds after the cc expires. Should get enough to consistently outdamage Rabadon's against non-tanks throughout the game, but only when they are cc'd. Slows wouldn't count cause then everyone would use it. Would be a go to for champs like Lux, Ahri, Syndra, etc. who tend to initiate with cc then combo afterwards.
Tank Busting Item Stats: 120 AP Passive: Increase AP by 20%. (From the small Rabadon's cap passive) Passive: When hitting an enemy champion with a spell, mark them after a 3 second delay, and your next spell will pop the mark dealing 15% percent of maximum hp damage. If mages are to be played bot lane, they're gonna need a way to deal with tanks like ADC's can and an item along these lines would do the job along with Void Staff. It would be pretty bad against squishies with the delay, and with the long activation time it won't burst tanks, it will just assure they can actually be killed if there's no ADC around.
Take these numbers with a grain of salt, I was mostly trying to get some ideas out there and show that it is possible to release mage items that offer different things and can be used to better differentiate AP builds from one another.
or this one new items or
or even
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and the like, or if balanced on them, useless for everyone else.
, which is think is a much more balanced option than your suggestion