I auto'd (or rather did, when I farmed the event) Chapter 12, with an Ultimate Madoka (four slot), Madoka (two slot), and Ren (four slot) team. I went down the far left path, and only manually controlled the two boss fights (Riko clones as well as the final boss) so I could use Madoka's Magia. Just set it so you don't use Magia/Doppel at all while on Auto, otherwise they'll consider the single waves as "Boss" waves, and use them on fodder trash. I saved Ultimate Madoka and Ren's Doppel for the final boss, and generally had Madoka's Magia to go as well (despite using it on the Riko clone stage). I had my strongest Memoria equipped to Ultimate Madoka/Ren, with Madoka equipped with the %Magia Bar filled per battle Memoria (can't remember the name off the top of my head right now), and another one that gave her attack/bulk).