Instructions
Reach the Haunted Forest level. You go to this level after beating the mission titled "The Distress Signal."
Play through the level until you receive a note telling you that normal weapons do not harm ghosts. Save the game at the save point, if desired, and then head through the exit to reach the graveyard.
Walk along the main path until you see stairs ahead. Run into the grass and crawl through it slowly. If the ghosts see you, they start to drain your energy.
Crawl to the right when the path splits in two. Head into the building in front of you. Pick up the item on the ground, called an anemone. You need this to receive the Sunrays spell.
Exit the building. Run to the right in the direction of the flying fireflies. Pass the fireflies, and run into the cave ahead of you.
Use the anemone on the shrine inside the cave to learn the Sunrays spell. Leave the cave. Aim at the ghosts, and press the "RT" button to kill each of them with the Sunrays spell.