Cave of Mysidia

The Cave of Mysidia (ミシディアの洞窟 Mishidia no Doukutsu, lit. "Cave of Mysidia"), also known as Mysidia Cave. is a location in Final Fantasy II. It lies to the southeast of Mysidia, on the other side of a nearly circular mountain range. The only method of accessing the cave is via a small gap in the northeast section of the range's circumference.

The entrance to the depths of the Cave of Mysidia is blocked by a dark Doppelganger which will mimic the adventurer's every move and halt his way. To destroy it, one must offer the White Mask to the goddess statue below Mysidia, which will paralyze the Doppelganger, and then the Black Mask should be placed on the copy, which will destroy it.

Story
Firion and his allies venture into the cave after learning that the Crystal Rod lies within its depths. The Rod is necessary for entry into the Tower of Mysidia. After venturing through the cave's five floors and using the White Mask and Black Mask to overcome obstacles, they obtain the Crystal Rod and sail to the foreboding tower, where Leviathan sleeps.

Music
The Background Music that plays inside the Cave of Mysidia is called "Dungeon".