"I wanna be ready with a champ or two I'm proficient with once that time come"
Right there is your first problem. You need to go into ranked games ready to play any ROLE the team needs. You can't go in thinking, "I'll be our team's DPS/mage/tank", you never know who will get banned and who the people ahead of you pick. You should be proficient with 10-15 champs at least I would say, if not more.
Say you are last pick, your team already has enough physical and magic damage. Do you:
a. Pick Vlad and say "I'll build tanky"
b. Pick an actual tank
c. Ignore team needs and play w/e champ you "main"
I want to see your answer to this, trying to help not intended to be mean
TL;DR: Be ready to play one of the following roles at a moments notice: Physical DPS, Mage, Support, Tank
Being good at several champs in each role will make you an all around good player and a great teammate. For the love of god, don't be one of the guys that says, "I can only tank as Amumu and they banned him! Sorry I can't tank but I'm a good Teemo!"
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