The nexus is open, you have 1 fight to decide the final outcome of the match.
The fight starts, and the enemy mordekaiser ults your soraka support next to the nexus, he knows that the soraka won't be able to kill him, so he just kills the nexus. None of your team can stop him because he is untargetable.
How is this fair at all? A mordekaiser can use R onto a Tank or support champion, completely ignore them, and end the game. This is so Broken. He should be disabled from ranked queues right now. This shouldn't exist in the game.