Fighting for Strength of the Ages
Now, I don't think this keystone saw a whole lot of popularity. In fact, even I didn't glance on it a whole lot, and I'm a jungle main who likes to break the meta builds as often as I can do it, and I still never went for it. It felt like free stats with no real game purpose, and I left it alone for a long time. And then I played it. And I realized that it did have its niche. It's not in the free 300 HP that builds up through the game. It's not even in the strange mechanic that causes cheese results if you can AoE an enemy champion sitting on top a ton of cannons, and regen to full. That does make a chuckle here and there, but that isn't it, either.
It's the out-of-combat regeneration.
There are a number of types of champions out there. You have the
who have a crazy strong engage followed by limited usefulness after ultimate. You have the
types that fight it hard, and basically don't need to even leave battle to regenerate/shield up for round 2, even without a strong source of regen.
And then there are tanks who really need some help:

. The last group would be champions who need to back at quarter health, because they won't even make appropriate fodder at that state of the teamfight. Now, they can emulate the regeneration group with something like a
or
, but their regen mostly relies on staying out of combat, and sometimes visiting a jungle camp or two.
Now, despite being specifically better out of combat,
feels more like an in-battle regeneration item, in the second group, as it has the highest regen in the game on top of the out-of-combat.
fits there, too. If there is an item/mechanic that emulates the "burned opportunity" of the first group, you have a few choices:
. However, nothing really takes a melee champion out of the fight as meaningfully and deliberately as happens to anyone in this last group. Nothing, that is, except for Strength of the Ages.
So, as an example, Xin commonly can get to super low health, being utterly useless to the group, and everyone disperses without their initiator. However, because of his ability to climb back up in HP in neutral camps, he can regenerate out of sight, and still either have a strong presence in the fog of war, or can abuse this with a surprise HP jump when an enemy scouts their red buff. Xin can do this without investing a thing into regeneration, thanks to his heal ratios on his W. With Strength of the Ages, though, any other champion can imitate this, but with oodles of HP instead of AD Lifesteal or trickles of HP Regen.
That is what is fun about the keystone, though I doubt it could be abusively fun based on its lack of popularity and generally easy counterplay (don't get baited), and I hate to see it go, especially for what looks like a second-rate replacement. Sorry guys, but hard CC doesn't need to land any harder, and if it does, it will probably make it that much more imposing and abusable than it already is. I also hate the thought that I could get a keystone that would be useless no matter what I did to my champion. Windspeaker's Blessing is bad enough, but this is just too much.