The Scroll of Treasures shows unopened treasure chests on your map. The scroll can be reached from the bottom left room on the map (first column, bottom row) in the Chalice of the Gods dungeon. To get to this room, you must start three or four rooms above it in the same column and travel downward.
Once you're at the bottom of the room, shoot the cactus on the left side, then go through the passage on the left.
You'll end up in the room you see below. Touch the scroll and the achievement will unlock.