I really like this idea, especially in combination with some new harder to get achivements like the ones in the "Endgame, (map)specific quests/achievements" from the "Quest & Achievement Suggestions - Megathread". The achivements don't need to give huge rewards imo and it would give some incentive to grind out some maps which I haven't played in a long time. I know i could simply create the challanges myself, but I would get way more excited if I get a achivement in the end. Especially if I could even brag whit it 😄.