Whenever a creature attacks you or a planeswalker you control, reveal the top card of your library. If it's a Forest card, remove that creature from combat. Then put the revealed card on the bottom of your library.
1/22/2011 Removing an attacking creature from combat doesn’t untap that creature.
1/22/2011 Because Lost in the Woods will trigger once for each creature that attacks you or a planeswalker you control, it’s important to specify which trigger is associated with which attacking creature before revealing any cards.