In Seiken Densetsu 3, the Dark Castle served as a base of opperations for the Dark Prince and his demonic hierachy. In the game, the Dark Castle used to be called Light Castle or Lorimar Castle. Lorimar became doomed because the Dark Prince made a deal with the ruler of the Mavolia (the Underworld in the Mana series) and became the new ruler in exchange for destroying his own kingdom.
The level begins as the player ascends the stairs up to the entryway of the castle. The player is then greeted with an assortment of unique enemies, and long hallways as they appear in front of a locked door. Mario is also given a health bar, and collecting potions like any other power up yielded from blocks will provide more health if the player is damaged. Moving all the way to the left, dodging the enemies' sword attacks, and jumping over holes and lit fire pits, the player will eventually find a room at the very end of the hall in which two enemies must be defeated. After this is done, a message will appear, alerting the player that the fire is now weakened, and the fire pits seen lit before are now blue, and safe to walk on. Upstairs, the player can now navigate to the center of the long hallway over the now unlit fire pits where a door leads to yet another unique enemy. The dragon requires three jumps to defeat. A message then appears stating that the player has found a key, so that they may unlock the door back at the level's entrance downstairs. After a brief outdoor segment, the player is back inside to find a checkpoint, and must travel upstairs to find yet more new enemies, and soon after fight Carmilla Queen. With her defeated, there is a long and somewhat tricky gauntlet of moving platforms outside, then the player may gather the five Dragon Coins and encounter the Archdemon. It's all over at last upon his defeat.