conjecture :the black key could be similar to the knights templar( The cultural clash between Christianity and Islam that shook the world a thousand years ago has re-emerged as the central theme of modern life for millions around the world. This book illuminates the conflict's origins, tracing the development of secret societies formed by men who sought mysteries beyond the dogma of their own faith: the Templars, warrior monks who exercised their religious devotion through force of arms; and the Assassins, Islam's first monastic military order, who fought Muslim and Christian alike to spread their doctrine.
In addition to its chronicles of the Assassins and Templars, this absorbing history profiles the secret tribunals in Westphalia known as the Fehm-Gericht, a vigilante organization that conducted trials and executions during a medieval period of lawlessness in Germany. Originally published in 1837, this was the first book to offer information on these secret orders.) as a key opens a door a breach is a kind of door into another realm the mages once sealed the breaches and survived. marks are in turn empowering objects/fangs etc leading onto "breaches close, and doors open, but a marked thwarts them both. who will block The Black Key?" WHO not WHAT !HOw would we as a group go about blocking a key going into a (lock)maybe with some magick and marks and using the house s to band together
the voice remembers The Collapse and doesn't wish to return to those dark days, but still intones "under, over, side of mountain, end is opened by the key." And being as the end game has been spoken about perhaps you need to use the black key to enter the end which intern means the collapse all over again so you d be torn on using/joining(if its a cult/society)to gain access to it but with dire consequences for the rest of the continent .
Most likely this is utter rubbish as i have no real idea but thought it be fun to throw it out there anyway .