Darkness Before the Dawn

It's bad enough when Mercurymon corners you in a world of mirrors but then he uses Seraphimon's data to turn into ShadowSeraphimon. It looked really bad for Takuya but energy from Seraphimon's Digi-Egg let Takuya Fusion Evolve to Aldamon, who kicked the fractal code out of ShadowSeraphimon and Mercurymon.