Spoiler warning! This section of the article contains spoilers, or hints about the game's storyline or progression.
You might want to skip down to the next heading if you do not want facts about the game's storyline or plot revealed to you.
Unlocking gold doors
With the Gold Key in hand, we can now revisit older locations that were previously inaccessible. If you wish to find these for yourself, or do not wish to read any spoilers, do not read this section, and continue to the next page.
A man wanders around the weapon's shop of Osterfair, asking if anyone knows the location of the Armor of Gaia. Interestingly enough, there is a gold door behind the shop keep. It may not be obvious, but if you wander around to the opposite side of the interior of the castle wall, where the Travelers Gate is, the black spot in the wall lines up perfectly with that gold door. Use the key on the door, and you can walk into the shop keep's area. He won't like it, but there's not much he can do about it. You are free to SEARCH the two chests on either side of him, and you will discover a Magic Knife in the chest below, and the elusive Armor of Gaia in the chest above. Equip the Prince of Midenhall with this impressive armor.
Back where the game started, you may remember a dark corridor where you needed either the Gold Key or the Silver Key to explore any further. Now that you found the Gold Key, the treasure trove that was visible in the south portion of the castle is now accessible. Inside, you will find a few items of small use, except for one chest, which contains the Seal of Erdrick! This is the proof you need of your heritage. Hang on to it, as it is important. If you are playing the remix version of the game, you will also find other substantially more useful items, such as the Life Acorn, STR Seed, and Mystic Nut, which can be used to boost your stats.
Another important gold door in Cannock separates you from an old man guarding a treasure chest. Surely its contents must be important to be given such a large portion of the castle floor plan. If you visit this area and open the door, you will be invited to the contents of the chest. SEARCH it and you will find yet another valuable heirloom from the might Erdrick; the Shield of Erdrick. Only the Prince of Midenhall can equip himself with this strongest (uncursed) shield available in the game.
Another old man sits on his own in a small island within the town of Hamlin, where you broke the curse of the Princess of Moonbrooke. A small building sits to the right of the island, and is locked with a gold door. If you open it, you will find a staircase that leads down. Upon visiting it, you will notice a strange sight of two Gremlins locked away in a dungeon which you cannot yet open. It would be best to remember this location. Upon climbing the stairs on the other side, you will find your way to the old man's island, where all he will do is inform you of the assistance that the spirit of Rubiss will provide you with once you collect the five crests, not unlike the information given to you by the descendant of the Dragon Lord in Charlock Castle.
Behind this gold door, you will find a woman who declares the building as a sewing shop. She asks if you are looking for some Dew Yarn, and if you say that you are, she will respond by telling you that she is out, but she will politely inform you of where you can find some for yourself: on the third floor of the north Dragon Horn tower. Remember this useful information.
You have always been able to see what lies beyond the gold door that is tucked away above the staircase in the weapon shop of Tantegal, but now you can finally open it and talk to the resident inside. As you may have already suspected, this is indeed the cowardly king who fled the occupation of his throne in fear of a potential attack on his life by Hargon and his minions. Even opening the door and talking to him cannot restore his courage.
More business in Alefgard
There are two more things that you can accomplish now in Alefgard. If you are playing the original version of the game, then you can reenter Charlock Castle and explore the locked treasure room all the way at the bottom of the castle, on the same floor as the descendant of the Dragon Lord. However, this is not recommended as the items found down there are generally not worth the effort. If you are playing the remix version, you would have already had the opportunity to plunder its depth and collect the valuable World Map, which makes navigating the open seas far easier. The second task is far more valuable. If you used the gold key to open the door in Midenhall Castle, and opened the chests within, you have picked up the Seal of Erdrick. There is a rather grumpy old man who sits in the Monolith far to the south of Alefgard (where a man once performed a miracle by creating the Rainbow Drop out of the Sun Stone and the Staff of Rain), who refuses to deal with anyone who does not possess proof of their heritage. With the Seal of Erdrick in your possession, you have such proof, and by showing it to him, he will provide you with the Helmet of Erdrick, another valuable defensive item that only the Prince of Midenhall can equip. Once he gives this to you, he will have nothing more to say.
Unlocking prison doors
Once again, if you would rather try to discover all of the locations of the prison doors that you were unable to open previously, skip this section and read the section below about approaching Tuhn. What follows is a recap of all the interesting locations with prison doors. Before you explore these locations, don't forget about the prisons in Wellgarth itself. There's a lot of valuable information to be found there.
In order to reach the Midenhall prison, you first have to make use of the Silver Key while slipping through the tunnel to the right of the central corridor. Once in the prison, you have two choices, interview the prisoner on the left, or dare to approach the prisoner below. The prisoner to the left will "reward" you for freeing him by hinting that the Life Crest can be found somewhere dark on the way to Rhone. The prisoner below can only be approached by first unlocking the gold door, and then preferably casting Stepguard so as not to take damage from the barrier floor, than opening the prison door. Talk to the prisoner, and you will instantly find yourself in a fight with an Evil Clown. Though dangerous, this should be an easy fight. Upon beating the Evil Clown, you will find a treasure chest, and in the chest is the Staff of Thunder, a powerful weapon for the Princess of Moonbrooke, which also allows for unlimited free Inferno spells when you use it as an item in battle! NOTE: In the Game Boy Color version, the enemy disappears after the fight, meaning that you CANNOT get the Staff if he wipes you out!
Compared to the Midenhall prison, the Cannock prison is much easier to access, and far less interesting. Once prison bemoans his fate, while the other tells you about the Silver Key. Both prisoners could be just as easily spoken to through the bars, so don't waste time visiting Cannock just to open these doors.
When you last came to visit Hamlin, you probably did so with the Gold Key to access the old gentleman on the island. Along the way, you will have witnessed this bizarre appearance of some gremlins locked behind bars in a water jail cell. If you open the doors and talk to them, you will find yourself in a fight with two Ozwargs, which are a more powerful form of Gremlin. It will be a challenging fight if you are not at a high enough level, but by the time you gain the Prison Key, you should be all right. However, upon defeating the two of them, you earn nothing out of the ordinary. There must be something else to this jail cell…
In Zahan we found a large building towards the back which is said to be home to a powerful wizard. He is so powerful that he has laid a trap for any would-be plunderer who tries to steal his goods by covering the floor with barrier tiles. Have the Prince of Cannock cast Stepguard so as not to take damage when walking across the floor (and remember to recast it every time you step off the barrier and back on) and approach the two alcoves on the left and the right. In the left, you will find the Magic Loom, a special item which you will need. In the right, you will find an empty chest, unless you happen to be playing the remix, in which case you will be fortunate enough to find a Wizard Ring.