Dream Leaf

Dream leaves are consumable items introduced in Golden Sun: Dark Dawn. They play a central role to a sub-plot in Kolima Village, which must be completed to advance the game.

After clearing the Phantasmal Bog, players can purchase dream leaves from a vendor in Kolima. Dream leaves cost 600 coins each, and can be sold for 450 coins.

Encyclopedia entry: These leaves grant pleasant dreams to those who eat them. They grow from a rare tree in Kolima, and people travel far to buy them.

Plot significance
When eaten, dream leaves grant a person good dreams. They are harvested from the Dream Tree in Kolima, making dream leaves a local specialty, although they've acquired much popularity in Border Town. Unfortunately, prior to Matthew's arrival in Morgal, the Dream Tree had grown ill, tainting new dream leaves so that they produce nightmares rather than pleasant dreams. As a result, the people of Kolima had stopped selling dream leaves until a cure could be found.

Matthew's party came to Kolima hoping to acquire a Roc Feather, but soon found themselves aiding the locals with their problems. A citizen of Kolima took the young warriors to the base of the Dream Tree and gave them some dream leaves, hoping they could find a way to cure the Dream Tree. Matthew and his friends eventually drifted off to sleep, and soon found themselves in a dreamworld. As they navigated the eerie swamp, they encountered a creature that they would later learn was the source of the Dream Tree's disease. As soon as the creature was defeated, the heroes awoke in Kolima. With the creature eradicated, the heroes were able to cure the Dream Tree with a bottle of Hermes Water, given to them earlier in Port Rago by Briggs.

Uses
Dream leaves are used to enter a "dreamworld" in certain towns. If anyone in Matthew's party has a dream leaf in their inventory when staying the night at an appropriate inn, the innkeeper will ask Matthew if he wants to use the dream leaf. If the player chooses to use the leaf, Matthew's party will be taken to the dreamworld. A portal appears where the player entered the dreamworld, and entering that portal will cause Matthew's party to wake up.

As of Dark Dawn, dream leaves can only be used in two locations: Kolima Village and Border Town.

Kolima's dreamworld

 * Main article: Phantasmal Bog

After the Golden Sun event, Kolima was moved eastward, landing on top of marshland. The sudden appearance of the city made the land liveable, but resulted in the destruction of the marshland. The destroyed marsh, would make up part of Kolima's dreamworld, albeit in a fantastical state, with multicolored flora growing throughout a long maze. The dreamworld would be haunted by Sludge, a former inhabitant of the marsh, until Matthew's party slays Sludge in battle.

Border Town's dreamworld
Border Town was originally a trading town located on the border of Morgal and Bilibin. However, due to a series of events, Morgal's leader feared an invasion from Bilibin and ordered the border closed. This proved detrimental to Border Town's prosperity and may have led to the increased popularity of dream leaves in Border Town, allowing its citizens to dream of happier times when the border is open.

Since the border is open in the dreamworld, Matthew and his companions are able to explore the Bilibin side of the town. Along the northern cliff wall is a plant that can be turned into a ladder via the Growth Psynergy, granting access to the Haures summon tablet.

It is unclear if Border Town's dreamworld is constructed from the collective dreams of its inhabitants or if it is simply what Matthew's party envision Border Town should be like. If the former, the dream-Border Town could either be an older version of Border Town, prior to the border's closing, or a possible future for the town, after the border has been reopened. The pre-closing version seems more probable, as there are various subtle differences between Dream-Border Town and Real-Border Town, hinting that this dreamworld is set in the past.