[Mechanics] Counterbuilding

#Counterbuilding
###Introduction
Wether you're counterbuilding against your lane opponent or a onesided enemy team, there's basically two ways to approach this and two questions you should ask yourself.
###Strenghts
The first question to ask is: "What are my enemy's strenghts?".
Do you have an enemy who has a very good heal? An enemy who relies heavily on his attack speed? Any enemy who needs to crit in order to kill you?

Once you've figured out what your enemy's strenght is, you can start to counter that. Buy items or actives that counteract whatever they're good at. Sometimes this completely walls them , sometimes it lessens their advantage just enough for you to sneak a kill in. Sometimes they might not only excell in one category, so closely observe them and judge what's really giving you problems (e.g. Is it Hercules' crowd controll or his survivability due to his heal that's making him so strong?).

###Weaknesses
The second question to ask is: "What is my enemy bad at, where does he have a (major) deficit?" Does he not have any survivability? Does all his damage rely on his skills? Does he not have any escapes? Is he frail once his heal is down?

Once you know what your enemy's weakness is, you can try to build into that and completely wall them. Stopp them from using their own strenghts by abusing their weaknesses to such a poin that they become useless.

###Team vs a single player
Sometimes you have to look at the bigger picture and ask yourself if it's really worth to counter build against a single enemy. If you're playing in the solo lane, forget this part and counterbuild, **always**. For anyone else, it's not as easy as that. Do you really want to give up your one of your actives spots for an aegis only because there's a midlane Poseidon? If there's also a Scylla in Solo lane and a Ao Kuang in Jungle, it's definitely a good idea. Or  if he's ahead of your midlaner and winning every teamfight with his Kraken it might be worth it. But just buying an Aegis because you spotted him when pressing tab is a waste of an active spot.

Look at their team composition too - if they all have heals it might be a good idea to get curse, even if the heals don't seem all that strong on their own.

###Usefulness of counterbuilding items
Don't just buy any item; make sure you get an additional use out of it too. Once you've determined what you want to counterbuild against (be it strenght or weakness), look for an item that not only fulfills that role but also helps you out. If you're up against someone with lots of phyiscal damage and you want to get some physical defensive, look for an item that also helps your own playstyle, and don't just buy BoV if you've already got full CDR.