While there is no single official "Collection 109" for the Horus Heresy
For readers interested in exploring the Horus Heresy eBook collection, the following recommendations are made: horus heresy ebook collection 109
by Dan Abnett, which depicts the final confrontation between the Emperor and Horus. Curated & Specialized Collections While there is no single official "Collection 109"
This is the critical caveat. Black Library (Games Workshop’s publishing arm) does not sell an official "Collection 109." They sell individual ebooks, bundles of 3, or the occasional Humble Bundle. bundles of 3
To understand the value of a 109-ebook collection, you must understand the scale. The Horus Heresy is not a trilogy; it is a literary universe. Here is what you get in the full 109 set: