Catalyst of Aeons AD item, please?

So Catalyst of Aeons builds into Rod of Ages and the Hextech GLP-800 for AP champions, as well as Righteous Glory for tanks, but why is there no option for AD champions. [?]

The reason I really would like to see this is of course for the upgraded Eternity Passive. 15% of damage taken from enemy champions is gained in mana and 25% of mana spent is gained in health.

I do imagine that a lot of people will say that most AD champions would be better off building lifesteal, and they are probably right for AD carries as they tend to rely more on auto attacks than abilities, however AD casters are not as efficient this way. There is Death's Dance, but this doesn't do much for mana issues, for which there are already very little options for AD casters.

I really just think this would be a good additional option, but what should it build out of?

Well, as I mentioned, this would be best for AD casters, so CDR and/or maybe armor penetration could be good. Attack speed and critical strike chance are not necessary, in fact I think they should be avoided in this to prevent a new ADC item. Raw AD is of course needed, but I don't think it will need to be in the 65 - 80 range. I'm thinking 40 - 55 AD would be great.

So just to throw a few numbers out,

45 AD 400 Health 350 Mana 10% CDR

With just these base stats, I think it could be a decent item, and being built from and would be simple enough. Final cost could be about 3000 gold

I would however really like to see some kind of second passive or an active effect, but I am betting that this would need to bring the AD down a bit, or at least cut out the CDR, which would be fine, and easy to accommodate by replacing with and this would bring the cost down a bit as well. ... And this actually makes me think of this item as a direct counterpart to Rod of Ages. Maybe it could also be a stacking item? Idk, not really the way I would go, but something to consider.

So what do you guys think, Is this even something that would be useful? What item would you like to see it built from? (also consider that there could be a new component item released with it) What stats would be best? What passive/active effects would work well along with Eternity?