Complex sentence: Annie had been a previous victor and was reaped for the 75th Hunger Games but, an elderly woman named Mags volunteered for her, to spare her from what had previously made her unstable.
Split into simpler sentences: Annie had been a previous victor and was reaped for the 75th Hunger Games. But an elderly woman named Mags volunteered for her, to spare her from what had previously made her unstable.