Would the Three Metallic Arts operate in other worlds, or are they direct results of Ruin and Preservation and thus only operate in Scadrial?
To use Feruchemy or Allomancy in almost every case, one must have the right spiritual and genetic codes, imprinted upon people during the creation of Scadrial by Ati and Leras. To use Hemalurgy, one must first have someone with these right spiritual and genetic codes, then take the power from them. Other people on other worlds are not going to simply discover the Three Metallic Arts by accident.
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