Perspective: Looking at Strength of Ages from a different direction.
There seems to be a large body of players who have pegged the Strength of Ages mastery as 1. Jungle specific 2. Heavily under-powered for solo or in general compared the other Keystones.
Phreak recently released his thoughts on how runes play out in season 6. One detail that caught my eye was when he referred to the Scaling Yellow HP runes as effective as armor yellows. As in they are a safe bet regardless of your lane.
In the vein Strength of Ages can be seen as an addition to the scaling hp runes in that over time it basically gives you double the effect. But that is not why we are here. There are two important situations where Strength of Ages becomes powerful.
- Champions who have strong kits, passives, or interactions with health:
just to name a few. In lane this allows them to gain 15 scaling HP/Lvl runes at lvl 1 every 1-1:30 minutes not taking into account the occasional jungle camp doing so would increase your scaling HP runes within that time frame to ~21.
This allows you to do 2 things early. Stack Scaling health or use this mastery to stack armor or some other rune stat while still getting the scaling HP rune benefit.
- This where Strength of Ages becomes very powerful. To illustrate lets use
as an example. Since his rework there are 2 ways to build him.
Heavy APC:
etc.
Bruiser:
etc.
The problem is that while the APC does more dmg he is much more squishy and vice versa. People tend to go toward the more damage centric build. Regardless this is a problem for many tanky-ish champs or at least champs where tank stats play into their kit, they have to sacrifice that ability to to damage to some degree.
Lets takes a look at at three 1250 g items:
. Tiamat and Large rod are great for damage but you sacrifice HP. While J.Fist gives you more health at the detriment of damage. This puts any tank at risk against all in offensive champions:
who would build
. In a straight trade for trade death battle
>>>
.
But with Strength of Ages Tanks can buy
and still get some of the benefits of
allowing them to hit better power spikes while increasing durability. This would be beneficial for Bruiser 
But what about APC
. Well generally one of his main items is
. It is a great item, 100 AP 400 HP and a slow. But that is only 100 AP if he wanted to invest in more AP he is likely to go
as it still gives him an defensive edge, but he loses HP, and an additional item slot for 100 AP and 6700 gold in total. Strength of Ages +
, 300 HP 162 AP 3800 g one item slot. This is a massive power spike with substantial durability as you only lose 100 HP and 39 AP, but save an item slot for other beneficial items.
Here is another example, say I really want to optimize my item space while still doing heavy damage. I don't want to invest in two defensive items
, yes they give me nice defense and health, but I lose two item slots worth of damage. Strength of Ages +
one item increase both armor and MR and gives you relative high health allowing you to be flexible with another item slot, which can still be Tanky but more damage focused
.
Strength of Ages +
=
with more damage.
So hopefully looking at it from this light you can see the power and flexibility this mastery gives you in the right situations/ champions.