I'm trying to develop a 5th edition D&D campaign set in Eberron. I know that the cause of the day of Mourning is open to interpretation, but I would like to relate the cause to the Dreaming Dark. I would like to ask for some ideas about Magitech for transporting Quori to Eberron from Dal Qour, and placing them inside of warforged. Would this make sense canonically?
The Creation Forges that House Cannith uses1 to produce warforged are based on a Quori design.2 The quori used warforged during their invasion of Xen’drik some 40,000 years prior to the typical Eberron campaign. House Cannith found the ancient Creation Forges of that war in its expeditions to Xen’drik and has used them as the core of their own warforged production.
Notably, Dal Quor is believed (by the quori themselves) to undergo “cycles” of light and dark, where in each cycle the entire plane is wiped clean and starts afresh with the new paradigm.3 Right now it is in the dark half of its cycle; the quori invasion of Xen’drik occurred during the dark half of the previous cycle. So the current quori know nothing of those times—they are exploring Xen’drik trying to uncover their own past, the same as House Cannith is.
However, the original quori warforged were not sentient. That improvement was made by House Cannith barely 30 years ago. How they did it is a closely-guarded secret,4 and it’s very, very likely that even they are still guessing at a lot of the underlying mechanisms that bring it about. This piece of information directly ties into the question, “do warforged have souls?” which is one of the “Great Mysteries” of Eberron, up there with “what caused the Mourning?” And the books are intentionally silent on that question, to allow for a DM to make up their own answer for their own campaign.
To wit: the books don’t say how or why warforged are sentient, and whether or not this is due to a soul. They are equally silent on whether or not the warforged have souls. And the entire point of this is so that you are free to make up answers that allow, for example, the idea that warforged sentience actually comes from housing quori spirits. Nothing in any Eberron book will ever contradict you on that point, because these are things explicitly left undefined so you can decide to have your campaign run that way.
So yes, this is perfectly acceptable, canonically, and ties into a lot of the things we already know about the warforged.
Officially, that should be “used,” but Merrix d’Cannith, at least, has a secret Creation Forge that is still operational.
This is a very closely guarded secret; very few even within House Cannith know of this.
This is why the kalashtar were so persecuted in Dal Quor: they were intentionally trying to force a switch to the light half of the cycle, which they believed was survivable. The rest of Dal Quor believes that this would erase everything and everyone, and so their response.
Even more closely-guarded than the quori origins of the Creation Forges.