Why this word is great
MYSTERIARCH — [Noun] One who rules over or presides over mysteries, especially religious or sacred rites. From Ecclesiastical Latin mystēriarchēs ("one who presides over Christian sacraments"), from Ancient Greek μυστηριάρχης (mustēriárkhēs, "one who rules over religious mysteries"), from μυστήριον (mustḗrion, "mystery") + -άρχης (-árkhēs, "ruler"). Unlike "hierophant" (which interprets sacred rites) or "archon" (which governs without mysticism), a mysteriarch commands the unseen, the veiled, the arcane. It is the hooded figure at the altar whose whispered words make candles gutter in unison, the keeper of a locked reliquary whose key turns only under a waning moon, the one who knows why certain doors must never be opened—because some power lies not in revelation, but in the act of withholding.