Darksteel Brute

Oracle Text

Indestructible (Damage and effects that say "destroy" don't destroy this artifact.)

3: Darksteel Brute becomes a 2/2 Beast artifact creature until end of turn.

Card Rulings

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 their most recent turn. It doesn’t matter how long the permanent has been a creature.