Report System Integrity. Does it exist?
I was in a co-op game a few days ago with a person who literally bought no items and just charged up midlane for the better part of 30 minutes. We won, duh, but they still did it and somehow fed 41 kills in total. I checked this person's profile, and this seems to be all they do for multiple games everyday.
While co-op isn't serious like SR and TT, these type of people still create unnecessary difficulty for their teammates (who may be legitimately practicing and not as skilled). How has this person not been banned? How many 0-30+ with no items games of evidence do you need to take action?