Pyroxene Esoterica (輝石奥義, Kiseki Ougi) is a pair of keywords related to the Birthgem Deities, a series of campaign X-rares from the Advent Saga. Its Heaven counterpart debuted in BS40 and Earth in BS41. The text of the keywords reads as:
- When your Field (Trash) is "[Color] symbols only & three symbols or more, [Effect]
Said final effect is related to one of the color's gimmicks, occasionally an unusual variation of an effect, such as Juno's forbidding of setting a burst, or a rare effect, such as Julyre's summon limitation or August's banishing. This effect punishes players who mix colors, an abrupt change in the game, as most recent sagas had a pair of families which existed in every color and supported each other (Galaxians/Astral Souls, Sword Masters/Exalted Swords, Lords/Vassals, God-Kings/Ten Crowns), allowing for non-rush based mixed builds.