Master Thief

Theft on a lease, with the duration clause doing the work that a hard steal never has to: the artifact comes home to you while this Rogue stays on the battlefield, and reverts to its prior controller the moment the Rogue dies, gets bounced, or otherwise stops being yours. That conditional is the whole bargain. Where a clean steal resolves and stays put, this one ties a permanent advantage to the survival of a fragile 2/2, which means the body you stole the artifact with is also the body your opponent most wants to remove. The reward scales with how cruel the swing is: take an opposing mana rock and you net a tempo lead; take their wincon or their key engine piece and you have effectively two-for-one'd them as long as you keep the thief breathing. This is the artifact-flavored counterpart to the creatures that abduct opposing creatures under the same lease terms: an enters trigger that changes control stapled onto a humble body. Built into a blink or recursion shell, the temporary clause stops being a drawback at all: flicker the Rogue and you can move the theft onto a fresh, better target, or simply re-trigger it after the original artifact has reverted to its prior controller. On its own it is a fair tempo play; the design's interest lives in how loudly it punishes a removal-light opponent who has parked their game plan on a single artifact.