Allure of the Unknown
Card advantage with a hostage clause. The math is lopsided in your favor: you dig six deep and refill your hand with five of them, a swing few five-mana sorceries can match. The cost is the design's whole idea, though. You do not choose what stays and what goes; your opponent does, and the one card they pull from the pile is a spell they may cast for free. So the deal you are cutting is deliberately imperfect: the best card in the top six is the one your opponent is most likely to pull, and if it is a bomb it comes right back down on you at no cost. This is symmetry-with-a-twist design, the same forced-choice family as Fact or Fiction, but pushed to a sharper edge because the exiled card leaves your library entirely and lands in enemy hands ready to fire. It rewards a deck scrubbed of anything catastrophic to give away, which is a real constraint rather than a cute one: you want a top six where the worst-case free cast is survivable, or better yet a deck that runs so few explosive spells that the opponent's best available steal is a mana dork or a removal spell with no legal target on their side of the table. The tension between the raw five-for-one ceiling and the hostage you surrender is the entire point.
