Mirrodin is the name of the Magic: The Gathering expert-level block containing the Mirrodin, Darksteel and Fifth Dawn expansion sets. The Mirrodin expansion set, as well as the rest of the block, is centered on artifacts and was only the second set to do so since Antiquities. The percentage of artifact cards is much higher than in any preceding set. Each of the expansion symbols in the Mirrodin block depicts a legendary artifact: Sword of Kaldra (Mirrodin), Shield of Kaldra (Darksteel) and Helm of Kaldra.
