5: Warwick right now. Seriously. So dump. Honorably mention to release Vayne and release Xin Zhao and stuff like that.
4: Teemo
3: The system. You can't jump into a 5v5 game and do what you want, so you need several games to get an idea of a new strat
2: The Players. Blaming and flaming and generally having a bad time.
1: Using cancer as an analogue for bad stuff. I just can't laugh at that.
Miss Fortune was top tier for her aoe ult one or two seasons ago, so please stop saying she'll never be viable without mobility. Because she was, and she could be again.