Season 3 can't start soon enough, but I hope it goes into maximum suffering
Marco will use his scissors to come to Mewnie attempting to rescue Star from Toffee, but he'll realize too late that he just doesn't have the kind of power necessary to stand up to an evil lizard demigod, so instead he strikes a deal: Toffee can have his body, his scissors, and earth and in exchange for the safety of Mewnie and especially Star, naturally mirroring the season 1 finale. Toffee accepts, since being stuck with Ludo isn't exactly the best situation for him anyway, but since he now basically owns Marco he has no obligation to follow the terms of the deal, as if he had any obligation before. He uses Marco's body to confront Queen Moon since Toffee knows she wouldn't dare harm Marco since she believes that he and Star are involved, and Mewnie falls under Toffee's control, and now that he has Marco's scissors, he can conquer the rest of the multiverse at his leisure.
At this point, Marco has given up everything for Star's sake in a vain attempt to set things right, and at the same time Star has lost everything: her friends, her home, her family, and her first love. Despondent and alone, she turns to Eclipsia's dark magic, studying everything she can to find a way to kill Toffee and take back what's hers