If I ever build another campaign, I am going to have a meta side story where the players are asked to save the GM from a dungeon filled with “shiny math rocks”. They’ll be like the inverse of a mimic: they’ll be bright shiny primitive solids, and depending on a roll from the related dice, they’ll change form into a monster as many times as they have sides, and the monsters will be ranked in increasing difficulty. If they save the GM successfully, everyone in the party will get a free pass to roll with advantage.