Terraform is a keyword that was introduced in the Heralds of Galactus expansion.

"Terraform" is a keyword on cards that represents a payment power that functions in the hand. The keyword "terraform" means, "Reveal this card >>> You may return a face-down resource you control to it's owner's hand. If you do, put this card face-down into your resource row. Use only if this card is in your hand and only during your recruit step."

- The revealed card goes onto the chain with this effect. If the effect leaves the chain before resolving, or if the modifier's controller does not return a face-down resource to his or her hand, the revealed card goes back to its owner's hand.