Warhammer 40k - Mark Of The Xenos.pdf ((free)) -

The current PDF version of Mark of the Xenos is sold by and is available on platforms like DriveThruRPG. It's a 146-page, full-color document in PDF format, priced around $20.

It is a testament to the writing team that many concepts born in these pages—specifically the detailed variations of Tyranids and the terrifying Rak'Gol—have been referenced in fan works and subsequent Black Library novels for years. Warhammer 40K - Mark Of The Xenos.pdf