Kindred's R lag
Today this bug cost me at least 2 or 3 deaths. I believe we would have lost the game anyways (and it was a normal one) but this should be fixed. I just went into a fight and when I was about to die I pressed my R. Nothing happened. I thought that I pressed it too late so I continued the game nromally, but this repeated through 3 or 4 teamfights.
When we were losing, the enemy Darius was mocking in front of me, leaving me at 1 hp and not killing me, and then I pressed my R like a crazy man about 30 or 40 times. It only went on when I was away from the Darius, and then I could confirm that it was a bug, not just my reaction time.