The Game Boy Color exclusive bonus dungeon!
A few notes to close things out.
- You need 155 Bronze medals (one for every monster seen to that point) to pass the first checkpoint in the cave, and 155 Silver medals to pass the second. Golds are just for funsies; you can collect them all and show the GranDragon, and he acknowledges your feat, but you get no reward for it. This appears to have been a last-minute change, as there's unused text in the game indicating that you'd originally have to find all the gold monster medals to fight him.
- You can trade two Bronze medals for a Silver medal with the second checkpoint guy in the Ice Cave, which cuts down on the grind. You know, if you're doing this legit.
- If you manage to defeat GranDragon within 25 turns, he awards you the Rubiss sword, the game's ultimate weapon. Any class can use it, it casts Thordain when used as an item and is 40 points stronger than the Kings Sword.
- Strangely enough, there's also a full set of monster medals for Dragon Quest IV hidden in the game's graphics. This suggests the game was originally intended to be a double-cart as Dragon Quest 1/2 on the Game Boy Color was, but for whatever reason this plan was scrapped. DQIV would eventually be remade on several platforms (Playstation 1, Nintendo DS and iOS/Android), but no version of the game features a Monster Medal system.