Quick! Quiz time! You're just starting a huge
Stun him? Snare him? Suppress him? All excellent answers. There's just one problem.
Your team composition is Fiora, Evelyn, Talon, Kog'Maw, and a Karma. You don't have any of those “stun” things. Unfortunately, in this case, the enemy Master Yi simply runs right through your team and slaughters all of you, easily
The lesson here is, I imagine, a rather obvious one. Put a Malzahar in your mid lane instead of Talon, and you get a totally different story. Instead of the Yi running through your whole team like an avenging angel of death, he instead gets tagged by Nether Grasp and has to watch as your crabs rip his face from his body in quick fashion. Put a Nautilus in the top lane instead of the Fiora, and the Yi would have been stunned for three seconds straight upon entering the fight, ample time for your team to rip him to pieces. Hell, even the ability to tag him with Chains of Corruption from a Varus pick would have been invaluable in this situation.
But, you say, I can't choose what my teammates pick! It's not my fault that my team chose such a bad team composition.
But, I reply, I'm not asking you to be accountable for what your team is picking. All you need to do is keep an eye on what the team is picking and pick accordingly. While you might not be as comfortable playing Zac and you are Evelyn, you're still way more likely to win if you have some crowd control than none. For a good half of the roles in the game, there's really no excuse for being unable to pick a crowd control heavy champion when required, as it's not as if there's any lack of choices for supports, top laners, and mid laners to pick from.
If, however, you truly don't play any such champions, no matter what role you play, then you should make learning one a top priority. You will win vastly more games that way. As a quick recommendation, top laners should look into learning Nautilus, junglers should always be able to pick up Elise if necessary, mid laners can always play the relatively skill-independent Annie, ADCs can pick between either Varus of Ashe, while supports can choose between a plethora of