She-Ra: Princess of Power (1985)

S1E22 The Crystal Castle

The liberation of Castle Bright Moon from the Horde's clutches hinges on a single, enigmatic condition: the Troll King must impart a secret to She-Ra. Only with this hidden knowledge can the fortress be reclaimed. The fate of the rebellion rests on this exchange, forcing She-Ra to seek out the elusive monarch and earn his trust, all while the Horde tightens its grip on the castle's ancient halls.