Magic: the Gathering - Datenbank

Trample (If this creature would assign enough damage to its blockers to destroy them, you may have it assign the rest of its damage to defending player or planeswalker.) Colossus of Sardia doesn't untap during your untap step. [9]: Untap Colossus of Sardia. Activate this ability only during your upkeep.  [Buried under a thin layer of dirt, it was known for centuries as Mount Sardia.]