You received a secret missive from The Merry and Green. Read the letter and perform the mission.
Step 1. Check in at the Danaria Green Hat BranchThe southern branch of The Merry and Green. They are led by Ubarunerk, Dairunrunerk, and Algarunerk..
Step 2. Sprinkle the Pure Purification PowderUse it to purify the Corruption Source. at Corruption SourceA severely contaminated area in Keliden Swamp.The corruption is so strong it seems unlikely it could ever be restored..
Step 3. Report the results to the Danaria Green Hat Branch.