Ruby Red. Catalog Number: 161291 Color: Red Format: LP UPC: 39841612912 All of Mercyful Fate's potential was fulfilled on Don't Break the Oath, a doomy, gothic collection of post- Priest/Maiden black metal preoccupied with Satan and the occult. Hank Shermann and Michael Denner keep their progressive rock tendencies reigned in while still delivering plenty of the neo-classical feel that gives the music its atmosphere, and King Diamond uses his vocal range to great theatrical effect.