Without anyone in your party except for Mardek (use a save crystal to change party), go to Lake Qur and talk to Elwyen. With her in your party, go back to Canonia in the cave in the north and talk to Gloria. With her in your party, go to a new location named “Dreamcave” north of Canonia. Walk into the dream circle. Explore the new area until you find a plot item called Amulet of Oneiros. Presto! Now you can enter any dream circle by simply walking into it!