I honestly feel like Keystones were a mistake.
Of all the changes this season to the different classes of champions, the itemization changes and even dynamic queue: none of this bothered me too much. Sure, the ADC rework was frustrating but I expect an entire class rework to throw balance out of whack a few patches. Same with the current Mage update taking place now, I expect the next few patches to be a bit whacky. And while I'm not super fond of dynamic queue, I do like that I get my top two roles every game. So I've learned to live with a lot, as you can see.
But to me, the one thing that was an absolute mistake that should simply be reverted are keystones. Initially I thought they would be cool but I realize now the reason we were so content with the old masteries is that they gave extra stats for a desired setup and were bland - but they weren't exactly game changing. And that sounds boring but had anyone ever thought of the alternative?
These masteries have basically only had about 3-4 be competitively good. No-Funderlords, Grasp of the Unkillable tanks that 100-0 you, Windspeakers and Fervor. You had some abuse cases like warlords but overall, these 4 masteries have been the most dominant, bond of stone had a short run. I actually think strength of ages is exactly what keystones should have been, a scaling keystone that didn't give immediate power but made your build pathes feel more flexible.
There are so many variables to consider when balancing this game and the only thing keystones have done is add another complex variable to several complex variables. They have warped the meta, they have warped what's strong and weak, they have given champions who ordinarily didn't have burst damage in their rotation an extra spell that added random damage. They gave champions who were balanced around the idea of not having sustain being a weakness. They were balanced around the idea of a champion being DPS focused, not random burst every 20 seconds. These masteries have thrown so many things out of whack because it's made several classes extremely oppressive (most notably ADCs and tanks) while leaving many of the other classes feel weaker because they can't abuse the masteries as well (mages, fighters).
I honestly think they need to be scraped next season. Just throw them out, they warp the game so much in ways you can't even feasibly balance around without making major class changes. Rethink them, I like scaling masteries like strength of ages that aren't immediately powerful and they don't just give more random damage tacked onto something at once or for the duration of a prolonged attack. Scaling is what makes them interesting and doesn't warp the game because scaling isn't assured and because of that it's not as immediately powerful.
on bard you can use thunderlords in 1 hit. =)
deathfire
bond of stone
50/50 on adcs : fever/ warlords
Most jg: strength of the ages, but many other options
and storm raiders is getting really popular of fiddles
who got totally sejuani'd because of the keystones