I hate Keystone Masteries.
Long text, if you don't want to read all of that, scroll down to TL;DR below.
I don't know how about you, but I just hate them. Imo, they were an unneeded addition to this game that brought nothing but chaos in balance of all champions. Not only that, they are just uninteresting for me, they require no interaction from player, most of them are just free damage or free stats so you can either outdamage your opponents or outsustain in some cases. They just add even more stat checking.
But, let's go through every keystone and briefly describe it, as well as mention what it brought to game balance: Warlord's Bloodlust- if I crit, I heal myself and get attack speed buff so I can outdamage my opponent. So yeah, heal + damage, just so I have to rely even more on RNG stat. And if I'm lucky and crit, well, I'm rewarded even more for my luck. Very uninteresting in design. Also, made Trynda and Yasuo unbelievably broken for a while. Fervor of Battle- my auto attacks deal more damage. Again, no originality, just free damage because you took it. Made Trundle and some other duelists a bit unbalanced for a while. Deathfire Touch- a mastery for DoT champions only, again, the only thing it does is increase your damage output. Do you see a pattern already? Also, it led Brand to become imbalanced and caused nerfs to champions like Karthus and Swain because Rito thought they are going to become OP. Stormraider's Surge- surprise! It doesn't increase your damage output! Seriously, finally a break from shit we saw with previous 3. Also, it's my favorite Keystone in terms of design. Why? Because it gives Movement Speed. Every noob will make use of free damage previous masteries offered, but this one gives a stat only skilled player will make use of. Movement Speed gives you bigger chance of out playing your opponent. This little buff can be enough for you to kite your enemy, or properly reposition yourself. You have to think in order to make use of it and that's why I love it. That's how Keystones should work, give you opportunity to outplay your opponent, not outstat! Whoever designed this Keystone, kudos to you. Thunderlord's Decree- guess what? More damage!!! Seriously, fck that mastery, fck what it led to (League of Thunderlord), fck it's versatility of use, fck it how champions with bullshit loads of damage can deal even more damage to you. Again, uninteresting in design and requires no thinking process to use it. Next. Windspeaker's Blessing- let's make heals stronger. Because Soraka wasn't obnoxious enough. Grasp of the Undying- you start with mini Titanic Hydra passive. Again, no thinking process required to use it, you just deal more damage and heal yourself when you auto your opponent. Strength of the Ages- you get equivalent of 2 Ruby Crystals for farming enough monsters and canon minions. Good for health stackers, what else to say, it's just free stats because you choose that mastery. Bond of Stone- my second favorite keystone in terms of design, still required no thinking process to use, but at least the mechanic is interesting. It grants you and allies damage reduction, as well as transfers a bit of damage dealt to them to you. It's still unfortunately just another free stats, but the damage transfer part makes it a bit interesting, although you won't see any difference in-game.
You see what I mean? The only think these Keystones give you are free stats. They don't change anything in your playstyle, either you deal more damage, or are more tanky, or heal more, just because you have them. They have no real impact on your playstyle and only led to few occurrences of imbalance. The only Keystone that is well designed is Stormraider, because it gives you stat that helps you outplay your opponent, not outstat. Others are just uninteresting. That's why I hate Keystone Masteries, it's just free stats, free damage, free heal etc. just because they exist.
TL;DR: I hate Keystones, they were unneeded addition to this game. They give you nothing more than just free stats or free damage and require no skill to make use of. The only well designed Keystone is Stormraider's Surge, because it gives Movement Speed, stat that you need skill in order to use and outplay your opponent. Other masteries just created even more difficulties to balance game.