You may discard a Forest card rather than pay this spell's mana cost.
Prevent all combat damage that would be dealt by unblocked creatures this turn.
You may discard any card with the land type Forest, including Snow-covered Forest or non-Basic lands like Tropical Island, Murmuring Bosk, or Stomping Ground. You can even discard a card that is a land in addition to other types, such as Dryad Arbor.