A Craftsman of Dreams and Nightmares is a Quest in Divinity: Original Sin II. The Toyseller was once part of the group that designed the Tomb of Lucian, and as such, may have information on how to bypass the traps. Would you be able to find him?
Definitive Edition: This quest doesn't exist anymore and the tasks are done in the sub-quest "Wisdom of the Keeper" of the main-quest "Hammerfall".
- Speak to Toyseller Sanders.
- Persuade him to help you get through the Path of Blood.
At the Magister's vault beneath the barracks, you can find a book titled, "Report on the Toyseller" to learn something about this sourcerer and start this quest. Alternatively, Lord Arhu, once freed, can also tell you to seek the Toyseller's help to get into the Cathedral. Arhu telling you about this will grant you 53,900XP for this endeavor.
In any case, go to the Toyseller's shop, and persuade him (check or fight) to help you. If you spoke to Arhu, you can tell him that Arhu sent him to help you get into the path of blood and he will agree to help you, giving you a source amulet. You will receive 53,900XP and 96,950XP and the quest is complete.
Before you leave, make sure to head upstairs and interact with the locked desk with the painting of Alexandar, using the password "Giyora" to unlock the desk and take the scroll of atonement. If you succeeded in persuading him or persuaded him via Arhu's recommendation, you will not need to worry since you won't have to steal the scroll, but if you failed the speech check then you'll have to steal the scroll.
Both the source amulet and the scroll are needed to open the hatch in the Cathedral. The source amulet must be filled with source to be used to open the hatch. This can be done by equipping the amulet onto one of your characters and abosrbing source (via source vampirism, a Source Orb, etc) while already having their source points filled. The "overflow" source absorbed will instead fill the amulet, and once full this can be used to open the hatch in the Cathedral along with the scroll. Note that the many dead bodies by the gate to Arx can be an easy place for a lot of Source Vampirism.
- 53,900XP for speaking to Arhu and learning that Toyseller Sanders can help.
- 53,900XP plus 96,950XP for convincing him to help you get through the Path of Blood.