Messages

Even if it's been tapped for the cost to bring out the card who's ability is to untap your creatures.

so basically vast wood was tapped to be used for the cost of another card that when put onto the battlefield allows all creatures to be untapped. Now since vastwood was already tapped as a land does the other ability work on vastwood in the same turn as a creature even if vastwood was used to pay the cost for that card as a land.