All you have to do to complete this quest is drink the Pink Slurry and visit the four troll runes. Don't worry it's only troll brains with a pinch of psychotropic herbs, shouldn't hurt a bit. The first rune can be found due west of the camp up against the mountain ridge there. The runes are all carved on large stones which can be interacted with. The second stone can be found by following the path as it travels to the southwest. The path will then curve around and head up the mountain to the northeast, you will find the third rune behind the first hut on the norther side of the road, careful of the hut's inhabitant, an elite giant. The final rune can be found due north of the third in the middle of the field there. Return to Violet Harwood for your reward and another quest.
After completing this quest you can earn the achievement Message Received by reading the troll glyph in Dreadbone Shelf.