Now that the next pre-season hit and we have a bunch of new items to look at (and no green wards or mana pots???), I'm hoping to use this as a chance to develop a new skill.
Designing my own item builds!
How we get started though? What are some general rules in designing specific builds? I want to become more self-sufficient and be able to make my own, rather than always copying somebody else's. If it helps, I main support!
The most common mistake I see is designing full build, while not useless it will often get you in trouble when a build only works if it's complete.
You have to make sure that your first item has an impact on your champion, possibly even the first component or you may have trouble completing that uber OP build.
The next one is picking a build before the game and sticking to that, it will often get you in trouble if the buid doesn't fit. For example Damage carry builds usually work only if you are ahead, but when you are behind you need to switch gears or you gonna loose.
Pick one or two items that are essential for your champion, then vary the otehrs depending on the situation. If you can't get any damage out, because they kill you too fast, get appropriate defense.
Also your core items don't necessarily need to be the first ones build. Pick the one taht help your situation the most.
There is no point in "designing builds."
When buying items, you are fulfulling one of two goals:
The most important thing to understand is how each item works, and what need each item specifically fills, eg if you need vision, the Sightstone line of items is what you immediately purchase. After you understand exactly which situations each item addresses, you can then make decisions within the game. Do I need to address this need now and buys Sightstone or Mikael's as soon as possible? Can I afford to make an investment in a Zeke's or a Banner of Command?
Balance these two goals and pair that balance with a deep understanding of not only complete items, but also their components. If you can do that, you'll never need to refer to builds or guides ever again.
Well one thing I used to do was go into item sets (which is one of the tabs in profile in client) and you can click the blue plus to start a new item set.
Since you're support you could name one like "Tanky supports" or something then just think objectively about what items would be good for that class. So tanky supports are likely melee so you can make a starting tab you could place something like 
and 3 
or and 
.
Then under that you can click create new block and call it something like "Mid game" and think okay what do I need mid game well it's usefull to upgrade the gold income item so 
, need vision so 
, and 
.
Then you keep building like that thinking what does this class do and what items make it better. Like sticking with the support tanks you likely won't ever build 
because it's focus is dealing damage and as a tank you're trying to take more damage, however you might build 
because it lets you take more damage and it can slow the other team down.
When you finish you can click the "Maps and Champions" tab and set it for summoners rift and then you can select what champions that set will show up on (that way you don't have an item set for tanky supports that shows up when you're playing 
or somthing).
Other than that some general rules of thumb... cooldown reduction caps at 40% (45% if you have the mastery but you start with 5% then so you still only need to build 40%), if you build attack speed for an adc or yi or something it caps at 2.5 attacks per second (it still caps there on 
but his ability doubles his attack speed so he can get to 5 attacks per second).
Other than that just do some trial and error and make sure you don't have any items with the same unique passive like 
& 
. Also make sure you're not making a static build path and you give yourself options in games. like 
can be a great item but make sure you have other options for in case the other team is all AD.
Lastly if you do make item sets they will show up on the recommended tab in the shop there will be a drop down arrow and you can change it from recommend to the set you named. Hope this helps a bit.
I would look at items that synergize well with your champions passive and abilities.
For example Nasus his W(Wither) is a movement and attack speed slow. So I always get a Frozen heart because of the stats and the 15% attack speed reduction Aurora. Also Randuins omen, the movement speed slow on active plus the cold steel passive on hit(15% reduction).
Another example is when I play Shen, most people build him tank(not my style). I build for burst damage. So things come to mind like Trinity force and lichbane. But I go for lichbane because I proc it with my passive(burst magic damage). I also add a hextech gunblade and rageblade (awesome on Shen). With also thunderlords decree(bit an enemy with the keystone, passive and lsheen from lichbane? That's a lot of power.
Those are just 2 exmples on what I do when looking into modifying a build. There is probably a more In depth explanation of theory but this is what I do haha.
