
Mistborn: Secret History is a companion story to the original Mistborn trilogy.
As such, it contains HUGE SPOILERS for the books Mistborn (The Final Empire), The Well of Ascension, and The Hero of Ages. It also contains very minor spoilers for the book The Bands of Mourning.
Mistborn: Secret History builds upon the characterization, events, and worldbuilding of the original trilogy. Reading it without that background will be a confusing process at best.
In short, this isn't the place to start your journey into Mistborn (though if you have read the trilogy - but it has been a while - you should be just fine, so long as you remember the characters and the general plot of the books).
Saying anything more here risks revealing too much. Even knowledge of this story's existence is, in a way, a spoiler.
There's always another secret.
Liam@liam★ 8.3
Mistborn is such a good trilogy and had a satisfying ending so I was a bit worried this would Ruin that but this additional story, that floats parallel to the 2nd and 3rd books, is such a great addition and adds some grounded, extra weight to the ending while also expanding the wider universe lore to give a greater understanding of the Cosmere.