From Sonic Retro
The Mystic Melody is an upgrade available to all characters in Sonic Adventure 2. It enables the user to activate mystery ruins scattered about the stages.
Sonic Adventure 2
- Purpose: It allows the characters to activate the various ruins found in the stages.
- Location: Please refer to the Sonic Adventure 2 upgrades for character specific locations
- Requirements: None.
- Required For: Each level has 5 missions. It is needed to complete the 3rd mission as it lets you get to the missing Chao. Nothing in the story requires this. But certain levels like Death Chamber, City Escape, Iron Gate, and Final Rush would be best to have it so you won't feel the need of breaking your disk in two.
- Equivalent: Everybody gets Mystic Melody.