Neo-Geildon is an evil "embodiment clone" created by Space War God Borudosu in the film Zyuden Sentai Kyoryuger vs. Go-Busters: Dinosaur Great Battle! Farewell, Eternal Friends. Not the original Darkness Messenger Geildon (in actuality Mahoro's brother and Asuka's childhood friend who died rather early in the invasion from Dino-Earth of Invasion Garden Evolian), he is an evil embodiment of the regret of the Evolians in their failure to defeat the Abaranger in the past.
Ultimately after the defeat of Borudosu, Geildon uses the collected energy from Geki and Ryouga to transform into Neo-Messiah, an embodiment clone of the Go-Busters' enemy Messiah. It is in this form he is defeated by a new Sentai team, the ToQgers.