I've just created a new account where I plan on never buying a champion until I want to start using it as a smurf account. I would consider myself a good player - currently Silver III - for how little I've played the game, but I find a big weakness in my game is that I don't have a good understanding of all the champions and their abilities. For that reason I created this account, where I will be forced to only play champions that are free that week. Throughout this guide I'll be including notes of the strengths of the champions that I play, and will probably keep a running list near the top.
OP - These champions can wreak hard. I typically won't but hard to play champions in this tier. I'm not a pro, and if you're reading this, neither are you.
Strong - These champions when played decently will carry you to victory. You'll also find the OP champions that are difficult to play here as well.
Average - These champions are good picks. If you know how to play them you can carry your team to victory, but if you don't, you're going to struggle.
Weak - These champions take a great amount of skill to do well. If you're not good at this champ, you'll most likely feed the other team all game.
Week 37 - Amumu, Annie, Diana, Draven, Gangplank, Graves, Leona, Nautilus,
Bot (ADC) - Draven, Graves
Bot (Support) - Leona, Thresh
Mid - Annie, Diana
Jungle - Amumu, Nautilus
-Amumu - OP
I've played Amumu plenty of times before, so I didn't need to play him during the free week to know what he can do. In my opinion is the strongest jungler in game right now. When I say this, remember I'm not a pro, so I'm talking about lower elo. He's also OP because you don't have to be very good to make game changing decisions. His ult is insane in team fights. There's a reason he's banned 99% of the time in the ranked matches I've played. When he isn't banned, he's picked, and I've never seen a team with Amumu lose.
Top - Gangplank, Shen