The towering Mother D-Reaper is the final form of the D-Reaper. After Beelzemon was cut down when he and Gallantmon were attempting to rescue Jeri from the Kernel Sphere, the D-Reaper had gained enough energy from Jeri’s mind to allow it to evolve further. Absorbing the Hypnos towers into itself, the D-Reaper became the Mother D-Reaper, forcing the Digimon to retreat, leaving the creature to spread itself further, and to begin making contact with the other D-Reaper masses that were located all across the globe.
When the Mega-level Digimon entered the D-Reaper’s chaos to wage the final battle, their path to the Mother D-Reaper was obstructed by armies of Agents, as well as the Cable Reaper. While everyone else took on the Cable Reaper, Gallantmon focused on the Mother D-Reaper, but was cut down as the Jeri-Type Agent emerged from it’s mass in the form of a huge head, and blasted him from the sky. Grani then appeared, and merged with Gallantmon, creating the awesome Gallantmon Crimson Mode, who destroyed the head, tore through an army of Horn Strikers, and defeated an advanced version of the Jeri-Type Agent in a fierce battle. Jeri had been able to crack the Kernel Sphere – located in the centre of the Mother D-Reaper’s “face” – with her Digivice, but chaos began to spill in, and, as Gallantmon moved to grab Jeri, the Mother D-Reaper’s tentacles reached for him, but before they could ensare him, the Mother D-Reaper - along with the rest of the D-Reaper's chaos - was sucked through the vortex back into the Digital World and devolved, thanks to MegaGargomon and the Juggernaut.
The Mother D-Reaper first appears in “D-Reaper’s Feast.” It’s voice, like the rest of the D-Reaper, is supplied by Bridgette Hoffman.