The Book of Omens (S04E20)

New Thundera is on the brink of destruction, and the Thundercats are tasked with retrieving specific artifacts from perilous locations that were once stunning sites. Meanwhile, Lion-O must enter the book and deliver the Key of Thundera to the book's guardian "at the 24th hour," or risk the Thundercats being trapped in time and New Thundera facing annihilation. However, Mumm-Ra seizes the book and key, entering it with plans to save New Thundera while freezing the Thundercats. The Ancient Spirits of Evil attempt to thwart him, fearing their own powers will diminish. As the other Thundercats face challenges at their respective locations, Lion-O uses the Sword of Omens to confront Mumm-Ra in a magic-free duel. Despite Mumm-Ra's underhanded tactics, Lion-O emerges victorious. The Ancient Spirits then unleash their "champion," Pyron, to take on Lion-O, but