GIVE IT THE WARMOG'S PASSIVE! No, really! Maybe have the Mana Font increase to 2% or 3% after not taking damage for, say, 6 seconds. This would make it a genuine man sustain item that can compete with Morellonomicon. Plus, it would feel worth the price as opposed to barely worth it after getting the ingredients.Broken? Good? Not Good? Discuss.
TL;DR: Warmog's for Mana
Actually, all Athene's needs to compete with Morellonomicon is to have the base regen bonus increased to +100%
Then, they'd both give the same MP5 bonus, and Athene's trades a bit of AP and the Grievous Wounds for MR and the increased regen based on missing Mana.
Maybe increase the regen passive a bit as well, but that's all you need to have them competitively comparable.
You're undervaluing Athene's far too much.
In short, regen is not why Athene's is the weaker item.
And now, why your suggest is very bad.
What Athene's needs to compete with Morellonomicon
How about mana sustain after not casting spells for several seconds.
Most mages aren't in a position to take much damage so you should make them get mana sustain if they save spells but no mana if they don't.
Done right, I think this idea could work to make Athene's the premier mana sustain item, without simply allowing you to spam continuously. The timer would have to go off whenever you're in combat or expending mana.
Thats stupid. Like, really stupid. What you're really looking for is of you don't use spells in X amount of time, but this broken as all hell.
Mana is a gating mechanic, you're basically trying to remove it without removing it. If you want something that that makes Athenes "worthwhile" then you'd want something along the lines of a harassment mechanic like:
Mana Font: Whenever you damage a Champion with a Spell, your Mana Regen increases between 50% to 400% depending on percentage of missing mana
Effectively turning Athenes into the Harassment item, allowing mages to negate Mana issues if they are consistent in their harassment of their lane instead of a sit back and Regen. It may have to suffer by giving no Regen otherwise (forcing you to constantly use your spells to harass), but we can't just make Athenes overtake Morellos just because.
Hell, I'd even be happy making Athenes an absorption item with stacks or something attached to it:
Mana Drink:
Passive: Every few seconds Athenes gains a Concentration stack. Whenever you Basic Attack or Damage a Champion with a spell gain X stacks
Active: Consume stacks, Gain X Percent of mana
While I do agree that Athene's is worthless, I think Riot should be careful with buffing it. There's nothing more annoying than 
being able to spam spells constantly in lane with no mana worries. At the same time, investing in a heavy mana item like 
should mean getting your money's worth.
There's a sweet spot here that needs to be reached.
You would probably have to increase the time taken and also have the condition that you can't cast spells or use mana either. I don't think Riot wants anyone to never have to worry about mana...
Athene's already does compete with Morellonomicon... Athene's still has the MR and still scales slightly better and still has good mana regen for spammy champs that stay low mana often. It also still has god levels of regen when paired with Tear or ROA. Your ideas not bad though and Morello is still better than Athene's in most cases, so it would be could for a verrry small buff to it.
I would honestly just increase the mana regen to 75%. Grail isn't hideously underpowered, just a bit.
I think riot doesn't want athenes to compete with morellonomicom..
I think morello is an item that you want to rush and not specially for the mana regen but for all the stats it grants.
Athenes is not a rush item anymore, it's an item you want to couple with an other mana + mana regen item to have a huge mana regen late game (I think tear/ROA + athenes as a 3th or 4th item).
They want those items to have 2 differents purpose. Morello is an early game really efficient item when athenes is a late game spam item.
My 2 cents.
Much applause, good sir. This is, indeed, a brilliant idea, even if it isn't implemented. I would rather it increase when you aren't casting spells instead, though, so it's truly analogous to Warmog's.
You see, Warmog's is like that so that you can be killed. It becomes a sustain item because the regen is not working when the resource is being consumed.
Athene's could have this passive when you aren't casting spells. That way, even if your opponent can't harass you consistently, you STILL can't spam spells with it. I believe this would be slightly better.
Really, what they need to do is change the stats on one of them. They can't both be the AP+ManaRegen+CDR item, that's too specific. Hell, we don't even have one Mana+MR* item, or one AD+Armor item. Let me tell you, champions that scale with mana have had happier days, like when BVeil had mana.
Not trying to troll but why do people hate the 2% of missing mana so much? I mean I prefer 
for the grievous wounds, but using both I pretty forgot I even had mana all the time.
Is their something I am missing?
IMO, just give it more MR.
I think it would be more fitting if the terms of increased mana regen were "After not using mana for x seconds, mana regen is increased by x%" instead of tying it with HP. Good idea though. Riot definitely needs to do something with mana regen.
How about 6 seconds after casting a spell?
Giving it more MR again is probably the best choice, that would differentiate it from Morello's in that Morello's for being aggresive, Ahtenes for being defensive.
