Search in the Chak Nest area for the strongbox from the 'Legacy of Owl.' 'Pride of Lions Arch' Strongbox Search in the Prismatic Postpile area for the strongbox from the 'Pride of Lions Arch. Follow the path shown, entering into the Chak Nest area. Fast Guide to Legacy of Owl, works no matter if you are in a closed map or full map. Once here, take a left turn onto the top of a tunnel.
This will take you directly to the strongbox.
