-For energy to walk through all the lands and summoning sprites, you must eat fungi, which (seemingly) randomly appear on the ground as pixelated, reddish rectangles. Tap once to make a circle appear around it. The Traveler will then walk over to the spot, pick it up and eat it.
-Also, you do not eat it or get any benefits from it at the point you pick it up. It is in your back pack. Open your back pack and select a mushroom to actually eat it and replenish your health.
Enter the dream world during a full moon by falling asleep by the hearth in the cabin. When you first see the Grizzled Boor, follow him to the titanic tree and enter to fight him. After defeating (but not killing) him, grab the key and return to the 'real' world. Go past the wall blocking the road to Mingi Taw, cross the stolid log bridge, and in the next area is a hidden door below the trail. Use the key to open the door. Once inside, you can manipulate the 'moods of the moon' at the bench.