With all three legendary artifacts of Erdrick in your possession, you are finally ready to confront the Dragonlord in his ominous castle. The Dragonlord's Castle is located on a secluded island, accessible only by using the Rainbow Drop. To obtain the Rainbow Drop, you must first acquire the Stones of Sunlight, the Staff of Rain, and the Fairy Flute. These items are found in various locations across Alefgard, often requiring specific conditions or interactions with NPCs. Once you have the Rainbow Drop, use it at the designated spot (usually a small peninsula) to create a bridge to the Dragonlord's island. Be warned: the castle is a labyrinth filled with the strongest monsters in the game, and the Dragonlord himself awaits at its deepest level.
