The dark battle hydra was a monstrous creature of Sithspawn origin which initially had two heads and razor sharp claws which could rip the flesh from its victims. Jedi Younglings at the temple on Coruscant were told tales about this creature, warning them that dark sith alchemy could cause these horrors… What the Jedi masters didn’t tell these younglings was that these creatures were actually real.
Many hundreds of years before the clone wars these creatures were created by a Sith Lord who wanted to experiment with dark alchemy and accidentally unleashed a version of the beast which would grow back 4 heads when one was cut off. Although the creature was used as a cautionary tale to young Jedi to stay away from the dark side, the beast did actually reappear to the students of Luke’s Jedi academy many years later, but it was soundly defeated.