Recommended lvl – 40
Travel to the Termes Palace Ruins. At the abandoned camp site, inspect the area with Geralt’s witcher sense to find a small box under some wooden boards. Inside you’ll find some notes that you need to read. Follow the map marker that appears to another part of the ruins. To the right of the purple door you’ll see a skeleton you can loot. From him you get another note (which you should read) and a purple gem. The gem goes into the slot next to the purple portal inside the ruin.
In the first room you will fight a few level 40 specters. Go to the left and blow out the wall with Aard. Past the new hole in the wall is a fight with a giant centipede (use Yrden). Follow the path to a second wall you can break down. Geralt will drop to a new area filled with even more wraiths.
To the right (on the map) is a skeleton buried under giant pieces of stone. Upon looting him you will find the first 3 diagrams we need. Now go to the left. There is a satchel lying on the floor containing the last 3 diagrams. If you continue on, you’ll fin a key sitting next to a locked door. Use it on the door to exit.