Trolls are not even afraid of the report system...
Honestly, they laugh about it.
And you know what? They are right. As long as they stay all nice in chat, nothing will happen to them. 3/15/2 Ahri with 3 boots? Nope, no problem at all, because she was super positive in chat always saying "we can do this" while walking into another tower to feed the enemy more.
And in post game lobby, she just laughed at us reporting her, because she just knows nothing will happen, because every report other than verbal abuse is just ignored by RIOT.