Heartseeker
Darksteel — rare
Artifact — Equipment
Heartseeker rulings:
2004-12-01: Heartseeker grants an ability to the equipped creature. The ability can target a creature with protection from artifacts (unless the equipped creature is an artifact creature).
2004-12-01: The equipped creature’s controller chooses whether or not to activate the activated ability. It doesn’t matter who controls Heartseeker.
2004-12-01: “Unattach Heartseeker” means just that — Heartseeker moves off the creature it was equipping and remains on the battlefield.