ThunderCats S01 E06

ThunderCats S01 E06 "Journey to the Tower of Omens"

While Lion-O practices with the Sword of Omens, Mumm-Ra forces Jaga to reveal the location of the Tower of Omens, where the Book of Omens is hidden. Lion-O struggles to use the Sword's Sight Beyond Sight until Cheetara encourages him with some very intimate contact. In the jungle, Snarf, while trying to fill his appetite, causes a ruckus which reveals the entrance to a temple leading to the Tower. After entering the temple, each member of the ThunderCats solves one of a series of deadly puzzles and reaches the Tower's entrance. Lion-O uses the Eye of Thundera and finds a button that opens the way to the Tower of Omens, which Tygra opens with his whip. Mumm-Ra reaches the Tower, having located it thanks to Jaga. A fierce battle takes place in the Tower, during which Mumm-Ra transforms into his muscular winged form. Cheetara is momentarily incapacitated and Lion-O attempts to save her. Tygra stops the young king, telling him the Book of Omens is more important than Cheetara. Mumm-Ra and Lion-O square off in battle, with Jaga sacrificing himself to save Lion-O and the others. The ThunderCats claim the Book of Omens, and Lion-O discovers it is actually blank.

Note: This episode was once titled "Journey to the Cat's Lair".