Instructions
Travel to the White Birch Forest located north of Midgards and accessible through the Valhalla Plains. There are no enemies in the White Birch Forest other than the boss.
Walk south down the second intersction from the White Birch Forest entrance. Walk east at the following intersection and then north at the third and final intersection to reach the unicorn. A cutscene plays involving Mint, after which you are in control of Cress at the entrance to the White Birch Forest.
Follow the directions in Step 2 to reach the unicorn again. However, at the final intersection, go south instead of north to reach a grassy area where Arche is. Speak to Arche to have her join your group and assist in the upcoming fight.
Walk north from the area where Arche is to find the unicorn and Mint. Your group is attacked by three Evil Lords, the bosses of the White Birch Forest.
Use spells that attack groups of enemies, such as Luna and Sword Rain, to inflict damage to all three Evil Lords at once. Use healing spells and items when you receive damage. Don't let any of your characters get caught in between two of the Dark Lords, as that character will receive a large amount of damage.
Defeat the Evil Lords by causing 10,500 points of damage to each one. When all three Evil Lords are defeated, a cutscene plays involving Mint and the unicorn. At the end of the scene, Mint receives the Unicorn Horn, which is placed in your inventory automatically.