Thought Dissector

Mind-milling with a payout: pay X, dig X cards deep into an opponent's library, and the first artifact you hit comes into play under your control while everything else gets binned. The design only makes sense in a world dense with artifacts, which is exactly the world Darksteel was built around. The cost is the lever that makes it gamble responsibly: a small X is cheap insurance that mostly mills, while a large X buys both depth and a wider net, since the activation stops the instant it finds a target. The catch is that you don't choose what you steal; you get the topmost artifact in their stack, whatever it happens to be, and the machine sacrifices itself to deliver it. That self-sacrifice is the honest part of the bargain: it's a one-shot theft engine masquerading as a repeatable tap-ability, since a successful hit retires the source. It rewards a specific read on the opponent's deck rather than a generic value plan, because its entire output depends on what is sitting near the top of someone else's library. As a piece of artifact-block design it captures the era's obsession with making everything an artifact load-bearing: the more artifacts an opponent runs, the shallower you have to dig and the better the prize, turning their own metal against them.