In Search of the Secret Spell (known as The Next Pyramid in King's Valley II) is a music theme originally composed by Masahiro Ikariko for the MSX game King's Valley II: The Seal of El Giza.
The theme was arranged by Michiru Yamane for Castlevania: Portrait of Ruin and is the background theme for the Forgotten City.
King's Valley II - The Next Pyramid
OST In Search of the Secret Spell ~ Castlevania Portrait of Ruin (Disc 1 ~ Original)
OST In Search of the Secret Spell ~ Castlevania Portrait of Ruin (Disc 2 ~ Arranged)