Chateau d'onterre is a side quest in Emerald Graves in Dragon Age 3: Inquisition. It initiates upon entry into the Chateau. Keep on the look out for a fast spinning cube after an attack by the undead. Don't be afraid of the cube, it adds a 10 point boost to cunning.
"An ancient horror has awakened in the Chateau courtyard."
- Gain access to the grand balcony. You must find a series of map clues that take you to the stairs, the bedrooms and the dragon before you can enter the balcony
- Kill the arcane horror.
- Boss: Undead
- Rewards: 967 XP, 200 Influence, 2 power
- Choices & Consequences: N/A
- Player Notes: Look for a mosaic piece for the Invasion set. You'll need to head up the stairs through the library and then into the section where the bedrooms are. You'll find an open window, overlooking the courtyard, that you'll jump through and the piece will be on a landing just outside the window.