How does the compass work?

In adventure mode, I've received a compass card for completing one of the battles. How does it work? Is there a certain place I should use it?

On Adventure Mode in the Battle Rewards section (top Left) there are 3 boxes.

• The reward if you earn an "A" ranking
• The reward for winning the battle in any rank
• The treaures that can be found on that map.

Sometimes the "A" Rank or Battle Rewards are blacked out with the phrase "Requires Search" above them. It might be possible for treasures to be blacked out as well but I have not yet seen this. This means that you need to search the map that the mission is on (pressing "X" to search, not A to start the mission).

So Press "X" to go to the map (not the mission). This will bring you to an 8-bit looking area with nothing else on it. Sometimes a sparkle is already present and the compass is not needed but it is not often. On the left side you should see all of the cards you have available (like the compass or candle). You can select and use the compass. It will ALWAYS work. So if nothing happens don't waste another one. It will then reveal a sparkling spot (if there are any) in which you would need to use the appropriate item to reveal the treasure as explained in this question: What does each item card do?.

Untested Speculation: Some zones say "the enemies are hidden". I have not tested this yet but I imagine the Compass will also reveal them.