Rod of Ages

What is this item ?
Most people think it's just a tank item for AP Tanks, such as ...
... and so on :D
Or as a clutch save in sticky situations for this guy :
But it's also something else : A massive sustain item.
It helps most of these Mana hungry short ranged pokees to survive in lane
and it also offers a very good late game scaling.
But there is one tiny problem with this item : It pressures the player into buying it early on and one of its passives gets useless at level 18.
So how can it be changed ?
Here's a rework suggestion :

Rod of Ages - 2900 Gold.
+ + 840 Gold
-450 Health
-450 Mana
-60 Ability Power
-Passive : Grants 20 Health and Mana, and 2 Ability Power per minute. Reaches the maximum amount at 10 minutes.
-Unique Passive - Valor's Reward : Killing a unit restores 0,5% of your maximum Health and Mana over 12 seconds, this effect stacks up to three times. Kills and assists restore 3% of your maximum Health and Mana instantly.

---

What do you think ?
Personally I think my concept is flawed, somehow, but nevertheless the original Rod of Ages concept is flawed as well and should be seeing some attention ;)
Please post your feedback, which will be constrictive and logical or have the word Teemo in it, in the comments :)

Edit : The Stacking simply means that they'll run simultaneously and that a maximum of 3 Stacks can run at one time, only when the first has ended you can add another stack.

Riot please test this or a concept similar on your fancy server and tune the numbers accordingly ! Please ! :D