The Horus Heresy #Novella (2011–2016) — book series in order

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Promethean Sun (2011)
Scorched Earth (2013)
Tallarn (2013)
Ravenlord (2014)
The Seventh Serpent (2014)
Cybernetica (2015)
Tallarn (2015)
The Unburdened (2016)