Invasion

Invasion is a mosaic in Dragon Age: Inquisition. "Pieces of an old Tevinter mosaic are scattered across the Dales. If recovered, they could be reassembled."

Walkthrough
The pieces are found around the Dales in the following locations:

Emerald Graves Exalted Plains
 * One piece in the Veridium Mines
 * One piece in the Personal Store room (adjacent to the Study) in the Villa Maurel. A warrior is required to break the wall
 * One piece in Argon's Lodge. It's in a room next to a log pile with a table that has weapons on it in front
 * One piece in Chataeu d'Onterre. It is on the left-hand wall to in the locked room off the Grand Balcony
 * One piece on a balcony in the Chataeu d'Onterre. You need to jump out of a window onto a ledge then jump to the top of a nearby building
 * One piece outside the door at the Din'an Hanin landmark
 * One piece inside of Din'an Hanin.
 * One piece in the final chamber of Unadin Grotto.
 * One piece at the Ancient Baths. It is behind a wall that requires a Warrior to break
 * One piece at the entrance to The Dead Hand. It's on a rock behind the Landmark
 * One piece in The Dead Hand (cave). It's on the left-hand side of the main room
 * One piece directly east of Lindiranae's Fall, in the rocks.

The recovered mosaic pieces can be seen on the left side of the Skyhold main hall.

Results
Recovering every piece of the mosaic and letting Gatsi translate it unlocks Codex entry: The Mason's Tales: Invasion.