It was always going to come to this… You're finally headed to the asylum. The Unspeakable Oath is the second Mythos Pack in "The Path to Carcosa" cycle for Arkham Horror: The Card Game, and it carries you deep into the belly of Arkham's asylum. You’ll find yourself behind locked doors, wracked by Doubt, and surrounded by Lunatics. And, still, you'll catch hints of deeper and darker secrets. And while its scenario continues and deepens the game's exploration of the mystical realms between the traditional roleplaying and card game experiences, its twenty-four player cards (two copies each of twelve different cards) provide you access to a number of wealthy Patrons and allow you to "learn" from your mistakes.

它总是会来到这个……你终于要去精神病院了。

无法形容的誓言是诡镇奇谈：卡牌版的“卡科萨之路”循环的第二个神秘档案，它将带你深入到阿卡姆的精神病院。你会发现自己被紧紧地锁在门后，被无限的怀疑所折磨，被疯子包围着。不过，你会发现一些更深层、更黑暗的秘密。

随着情节的持续进行，你将通过传统角色扮演和卡牌游戏深入探索游戏的秘密领域。游戏中的24张玩家卡牌（12种卡片各2张）将一些富有的赞助人，让你从你的错误中吸取教训。