Remnant From the Ashes Simulacrum
As you playthrough Remnant: From the Ashes you will come across the Root Mother. This NPC is trapped in The Harbinger Church and you must help her escape. Once you’ve done this (as part of the story), Root Mother will move to Ward 13. At Ward 13 Root Mother will upgrade your Dragon’s Heart for you. To make theses upgrades you need Simulacrum. Below I will briefly explain where to find this rare resource.
Where to Find Simulacrum?
As mentioned above Simulacrum is a rare resource. Because of its rarity the locations it spawns are random. With that said there is some concrete information I can provide you about locations. The most important thing for you to know is that one Simulacrum will spawn on each planet per playthrough. This means you can potentially gather 4x Simulacrum per complete game run. Alternatively could also simply farm Earth for Simulacrum by rerolling over and over again.
Hopefully you found this look at Simulacrum helpful. Due to the nature of the Simulacrum resource it is hard to provide concrete information, but at least you now know where to start your search. If you have anymore pertinent information regarding Simulacrum, drop it in The Pit below.