The Mirrodin block is the ninth block, consisting of the large expansion Mirrodin (), and the two small expansions Darksteel () and Fifth Dawn (). The block came out in 2003-2004.  Because it caused the second Combo Winter, Mark Rosewater considers it a low point in block development. 
Each expansion symbol in the Mirrodin Block represents the Kaldra artifacts: Sword of Kaldra, Shield of Kaldra, and Helm of Kaldra (Listed respectively to the symbols above, and also result as a mega cycle of Kaldra Equipment).
The theme of this block is artifacts, and the set introduced the first artifact subtype, Equipment.
Keywords introduced in this block: Affinity, Equip (which goes along with Equipment), Entwine, Imprint, Indestructible, Modular, Sunburst, Scry.