Karn, Silver Golem | Magic: The Gathering
Formats Karn, Silver Golem is Legal in
Official Oracle Text for Karn, Silver Golem
: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its converted mana cost until end of turn.
Official Rulings for Karn, Silver Golem
8/1/2008 : A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of his or her most recent turn. It doesn't matter how long the permanent has been a creature.