Basically by mastering them you simply have created a build that you own with. This means you know when to attack and when to play it safe without feeding the opposition. The best way to learn is play bots over and over till you know which items to buy. Once you've got your build down thats when you fight players as you wont waste time deciding what items to buy and when. Once fighting players you'll naturally gain experience of when to ambush, when to push, when to play defencively and so on. If you want someone to play with I can play some games with you from time to time. My name on their is Tyraes2208.