Exodus the Terrible
Exodus the Terrible is the heavy ominous tune that plays as you work your way through the depths of Exodus' castle. The first five notes of the song can also be heard when you play the Silver Horn.
The title is the translation of the title on the Ultima Mix album (恐怖のエクソダス, Kyoufu no Exodus).
Ultima: Exodus (NES)
The NES song is the original version of the tune. The song is track 10 in the NSF file and is played on the RP2A03.
Ultima: Fear of Exodus (MSX2)
The song was ported to the MSX PSG which gives it a flatter sound. It is track $0A in the KSS file.