Karn, Silver Golem

Legendary Artifact Creature    (CMC:5)

Whenever Karn, Silver Golem blocks or becomes blocked, it gets -4/+4 until end of turn. : Target noncreature artifact becomes an artifact creature with power and toughness each equal to its converted mana cost until end of turn.

6 V10 • ENMark Zug

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Legal in: Urza Block,Legacy,Vintage,Freeform,Prismatic,Tribal Wars Legacy,Singleton 100,Commander

Oracle Text (click to copy):

Karn, Silver Golem {5} Legendary Artifact Creature — Golem Whenever Karn, Silver Golem blocks or becomes blocked, it gets -4/+4 until end of turn. {1}: Target noncreature artifact becomes an artifact creature with power and toughness each equal to its converted mana cost until end of turn. 4/4

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10/4/2004
The blocking ability triggers only once no matter how many blockers are declared.
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.

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