You don't have to be a pro to adapt to all the changes. I was gold for a long time because I just copied other peoples builds. When I learned how to play the game properly by spending a little time understanding what champs, items, runes, and masteries are good in certain situations is when I finally reached Diamond. Understanding the game is the main part to adapting to it.
It's fairly simple when you open your mind to it. For example; when you are a tank, and you want an armor item, you get several to choose from, and if you always choose the same one first, you're doing it wrong. Each item has it's distinct advantages that make them best in certain situations where others would not be worth the money in that situation. The battle between Sunfire, Frozen Hear, Omens, and the others is an important thing to understand when building an armor item.
LONG EXPLANATION ON THE THOUGHT PATTERN I HAVE WHEN DECIDING BETWEEN MASTERIES WHEN I PLAY.
Same thing goes for masteries. The keystone masteries may look insanely hard to understand which to go for since it's all new, but only playing 25~ games on this new patch I already got a fair understanding of it.
Take Ferocity and Cunning mastery trees for example. Say you are building a bruiser champ, which usually tilts more toward damage first, tanky second, which usually leaves wanting damage from masteries first and tanky second. So you will want either a Ferocity ( pretty much always this for bruiser I think ) or Cunning keystone mastery. To choose which route you want to go, base it off your champion.
Warlord's Bloodlust: Great for champions that build crit, especially early. Early crit means sustain and %IAS for trades, and impactful late game against tank/bruiser champs diving you more than it benefits you from assassins ( still good against assassins, but not as much ). Just watch an end game tank try to kill your ADC who is running this mastery.
Fervor of Battle: Does your champ auto attack a lot? Great on a bruiser like Irelia as it synergizes amazing with her W, but even still good on a bruiser like Renekton, simply because you do not only kill with spells, but the damage from Auto's are important and this is a great damage addition.
Deathfire Touch: Great for champs that use single target spells, not as good on multi-target but still useful. This adds some decent damage to your spells.
Stormraider's Surge: Are you doing 30% to an enemy in 2 secs regularly in a game? not just late. This can be useful for champs that need movement speed to get out of a fight or re-position after chunking someone but does not need added damage the other keystone masteries give.
Thunderlord's decree: You can almost look at this as a luden's effect, but only occurs when you hit a target 3 times with any mixture of spells or auto attacks. This is helpful for any one who gets the mixture of 3 spells/autos on a target and needs burst to take them down. This keystone adds some unexpected burst to your kit when trying to kill someone. I love it on Riven, and other champs that are supposed to delete people fast.
Sorry for the long post, but I was hoping to give you a little insight in the thought pattern I have when considering which of the keystone masteries will best suite my current champion, matchup, or win condition. Other masteries are the same way, but the first step is to determine your keystone mastery, and then decide which masteries along the way to that keystone will benefit you the most. Try different ones out and see which you do better with, your playstyle is not the same as everyone elses, so it's important to remember a keystone someone else dominates with, may not be the one you should use to dominate with.
