I like getting Athene's to mitigate mana issues, but I've never tried getting it on an AD champ because of the wasted AP. Can we have a similar mana-boosting item for champs like Sivir, Olaf, Volibear, and the like?

Suggestion: new item that builds out of Brutalizer and Emblem of Valor.

40 AD
40 armor
15 hp5
10 armor pen
Unique passive: 15% CDR
Unique passive: 5% armor pen
Unique passive - Mana Siphon: Hitting an enemy champion with a basic attack or ability restores 1% of your max Mana.

Instead of passive mana regen while sitting around doing nothing plus a big chunk on kill/assist, mana restoration is more normalized. The different mana restoration is mostly for the sake of uniqueness, but if that doesn't matter it's probably fine. I just wanted some way to compensate for the complete lack of passive mp5 on either Brutalizer or Emblem. This item wouldn't help a nearly-drained Darius or Yi chain-reset-dunk for a penta, but I think that level of burst mana usage is pretty rare. I also don't think it would be another Ryze-secret-OP item like Muramana, because it has no mana and he really doesn't need any more CDR.

inb4 Manamune/Muramana

Actually, I already mentioned that. Ryze, as I said, works really well with Muramana. A few other champs can viably get it, but not many. It's the same with Archangel's and Athene's: few champions use Archangel's, but Athene's has a variety of useful stats that make it a great item for AP bruisers/supports/tanks.

Ok, a few points:

1: Sheen, Triforce, Manamune, and Muramana are all solid options for any physical-damage based champion with mana issues. Sheen alone usually solves them for the vast majority out there, and with Muramana's upgrade you can make it cost-effective when mana ceases to cause problems. Supports can also upgrade Mana Manipulator into a pretty swanky item, so seeing +mana regen on auras early on isn't as unlikely.

2: Tri-Force is the only item really deservant of having a salad of attributes (as that's mainly it's shtick). Most items in LoL are incredibly focused in what they offer. Muramana offers AD, Mana, and Rejuvenation for instance. Infinity Edge offers AD, Crits, and more crits. This makes discerning the purpose of an item rather easy, and also makes coming up with builds that can fit the item in it easy - as the item accomplishes one thing, but does it well. This has 7 attributes without even including the passive, which is a needlessly large number of stat values.

3: 1% of max mana would be around 3-10 mana restored per hit based on leveling, as champions tend to have somewhere in the neighborhood of 300-1000 mana from leveling. While 3 is clearly lower than the 4 offered by Manamune, 10 is kind of ridiculous. If you have 1.0 attacks per second that gives you the equivalent of 50 mana regeneration per 5. Athene's Unholy Grail only grants 15 mana regeneration per 5, and with the passive at 100% strength it bumps that 15 to 30, plus whatever other mana regeneration effects you have. Manamune and Muramana only have 7 mana regeneration per 5. Also, the passive is sort of counter-intuitive being % max mana based. From leveling alone you can get your mana pool to a level were restoring 1% of it per attack will make purchasing any additional mana or mana regeneration completely obsolete.

1. I honestly have never heard of people buying Sheen or TF for the mana (I think it's bought for the Tons of Damage), except for Ryze buying Iceborn Gauntlets. Manamune is barely bought at all, in most cases. Often, again, by Ryze.

2. The attribute salad, at 7, is almost identical to Athene's' at 6. Take out a single attribute, like the 5% ArP, and they'd be even (items usually improve upon every stat found in their component parts, and 5% ArP seemed more effective/engaging than just adding an extra 5 flat ArP). TF has 9. Gunblade has 6, Hydra has 6, a bunch of items have 5, and so on.

3. A mechanic like Mana Siphon is basically lifesteal, only it scales on mana instead of attack, and restores mana instead of health, and (importantly) only happens when attacking champions. You can't sit in brush or at tower and watch your blue bar fill up, not even if you're poking minions. Also note that it's supposed to replace Mana Font AND the 12% restore on kill/assist, which, in a large, successful teamfight, can restore 5-700 mana on its own in about 10-20 seconds (equivalent of 25-70mp5). Finally, Athene's makes additional mana and mana regeneration obsolete as well (even when not in combat with an enemy champion, to some extent).

I just wanted a mana booster for physical champs that more people might actually buy. =\

It would certainly feel more fun to me than repeatedly ending matches with a barely-half-full Tear/Manamune/Staff.

If u rush tear/manamune and u rlly use ur ability/attack ur tear will br charged quiickly...also voli doesnt habe mana isues. Would be useful on kha zix, tho

You guys keep saying "Manamune" and it keeps being an unviable item for all but a couple champs, a good portion of whom are mages (Ryze and Syndra). The idea here is an item that helps with mana that people might actually want to buy on champs that use mana but don't build AP. If such an item ends up being something completely different, that's fine - as long as there's a viable AD mana item.

Kha can use Manamune in a great way, it got build on him in nearly every match in the recent tournament, it TOTALLY negates his mana issues, he can charge it rpetty swiftly and it works pretty well on his Q.

As was said, no matter what you think, Manamune IS viable now, it works on many ad champs and is worth it on plenty of them, not on everyone, but not all ad champs are supposed to just be able to solve their early mana issues with an item, cause mana is what limites ad champs as they have their auto attacks besides their skills, contrary to ap caster champs.

Before S3, Manamune was largely a noob trap for most champs, as far as I'm aware. What changed? Which champs see regular and viable Manamune use now?

Well, manamune has an upgrade now.
It's still largely a noob trap tbh since most champs can't charge it well.
I've seen ez build it, synergises with iceborn gauntlet to give a little more ad.

Anyway, champs that viably build it is basically Urgot and Ryze to my knowledge. (it's core on them)