Legerdemain

A swap dressed up as a barter: you hand over one of your permanents and take one of theirs, with the catch that the two have to share a type. That shared-type restriction is what gives the card its character. It bends the effect away from a pure "steal your best thing" line (the way an aura-style theft or a clean control-stealer reads) into a trade where what you give up determines what you can take. The cleanest play is to donate something worthless that happens to share a type with the target you actually want: a token, a do-nothing artifact, a creature you no longer need. Either type works as the bridge, so a creature can be exchanged for a creature or an artifact for an artifact, and the rare crossover comes when a permanent is both. The sorcery speed and the indefinite duration are the two halves of the bargain: this is a permanent change to the board, not a temporary loan that snaps back at end of turn, but you pay for that permanence by being unable to do it on your opponent's turn or in response to anything. It sits among the older entries in blue's long flirtation with theft, predating the cleaner, cheaper takeover effects that came later, and the friction in its targeting is exactly why it never became one of them.