Graham McNeill
Forge of Mars

A great explorator fleet sets out into uncharted space, the Halo Worlds at the galaxy's edge. They seek an ancient and priceless technology from the birth of history, but what they find is more powerful and deadly than any of them could have imagined.
Warhammer 40k
omnibus

It contains:
Priests of Mars
Zero Day Exploit
Lords of Mars
Gods of Mars

Also in:
Eleven Tech Priests A Tinkering