To bridge the gap to the Dragon Lord's castle, you must create the Rainbow Drop by gathering three legendary artifacts. First, the Stones of Sunlight are hidden within Tantegel Castle; you must use a Key to enter the basement via the outer wall and 'Search' the ground in the hidden room. Second, you must acquire the Staff of Rain. To do this, retrieve the Silver Harp from the Grave of Garinham and present it to the hermit living in the shrine located south of the Swamp Cave. Note that the Harp is the only way to prove your worth to the hermit.
The final component is the Fairy Flute, which is essential for defeating the Golem guarding Cantlin. This item is hidden in the village of Kol; you must walk four paces south of the bathhouse and 'Search' the ground to find it. Once you possess both the Stones of Sunlight and the Staff of Rain, travel to the Sanctum located on the far southeastern island. There, the priest will combine these two relics into the Rainbow Drop, allowing you to manifest a bridge across the channel to Charlock Castle.
