In Peace

This is a late-game optional achievement, wholly in Hossberg Wetlands.

You have to make three flowers grow - this can be done by completing "The Cabin in the Blight" and then "Something's Coming". Both can be started by reading letters in the Lighthouse.

After the quests, you can go back and collect the flowers - one is where you finished "Something's Coming", another is in the Eastern part of Hossberg Wetlands where there are lots of blue flowers, and the third is in the Southeast - also near loads of blue flowers.

Once you've got them, return to the battlefield in the South where you battled the dragon and talk to the blue ghost.