Heather: "Hey, [Your Viking's Name]! I have a plan to get the sheep to take the medicine. Let's try making an herbal tea out of the plants. Go into the lab and we'll give it a go!"
1- Mix plants with hot water
2- Give Mildew the tea in Icestorm Island
Mildew: "What took you so long? Are you sure this tea will work?
Fine, I'll give you the treasure in exchange for the tea. Don't expect any more kindness from me! I put it with my things over there. Fetch it yourself."
3- Collect the petroglyph piece
Mildew: "You got what you wanted. Now leave me in peace!"
!: "This looks like it would fit in the Archaeologist's petroglyph. He would appreciate this piece you received from Mildew."
4- Give the petroglyph piece to the Archaeologist
Archaeologist: "My friend, this is amazing!
Click/Tap on the petroglyph on the table and look at it, [Your Viking's Name]."
5- Click/Tap on the petroglyph on the table
Archaeologist: "We're getting closer and closer to solving this ancient mystery, my dear friend!"