Animate Artifact

Enchant artifact
As long as enchanted artifact isn't a creature, it's an artifact creature with power and toughness each equal to its mana value.

30th Anniversary Edition

Masters Edition IV

Enchant artifact
As long as enchanted artifact isn't a creature, it's an artifact creature with power and toughness each equal to its converted mana cost.

Fourth Edition Foreign Black Border

Fourth Edition

Target artifact becomes an artifact creature with power and toughness each equal to its casting cost; target retains all its original abilities. Animate Artifact does not affect artifact creatures.

A noncreature permanent that turns into a creature can attack, and its {T} abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.

This card has been returned to its original functionality. If it is enchanting an artifact that's already a creature, it won't change its power and toughness.