The Cooper Gang

Commander Sneak {U}{B}{R} (You may cast this spell for {U}{B} if you also return an unblocked attacker you control to hand during the declare blockers step. This is tapped and attacking.) Other Thief creatures have Sneak {U}{B}{R}. Whenever a Thief you control deals combat damage to a player, you may choose one — • Search your library for an Artifact and add it to your hand. Shuffle your library. • Gain control of target Artifact.