Broken Multi Button challenge requires you to never press multi button.
This challenge doesn't look too hard at first but it is actually very hard one to try and get a win on.

Multi is used in calculation of your base powergain and improves effect of your biases. Restricting your multi to just x1 greatly reduces your powergain and therefore makes you a lot slower.
Winning the round is still possible, although highly depends on max_assholes count and overall activity in AH-ladder.