Moriok Scavenger

Recursion with a metal-only restriction baked into the qualifier. On a plane stuffed with Myr, Golems, and assorted constructs, an enters-the-battlefield trigger that buys back an artifact creature card from the graveyard pointed straight at the cards that era was built around. The narrowness is the whole point: it retrieves only artifact creature cards, dead weight in a deck that ignores metal and a steady value spigot in one that does not. The 2/3 Human Rogue is incidental, a fair-rate frame that exists mostly to carry the trigger onto the battlefield, where any sacrifice or bounce effect can loop it to keep returning whatever construct died last turn. It sits among a wave of color-specific graveyard recursion the artifact-matters period handed out across the wheel, each color getting its own flavor of getting things back; black's version pays for the restriction only when a build commits hard enough to artifacts that the qualifier stops biting. Strip that clause and it would be a generic Gravedigger variant; keep it, and it becomes a build-around whose value depends entirely on the surrounding cards doing the work of filling the graveyard with the right targets.