Maybe add an option to confirm the matchup before just flinging my best champs into a dungeon with some scrub using 3/30s and 4/40s.
I now have to wait another 2 days before I can use my 5* because of your broken feature. What's the criteria for a matchup? Is team power even taken into account? Champ levels? This is another crappy mode that makes players dependant on other people's skill level and availability and the issue is only compounded by shocking matchmaking choices.