Daemon World

Daemon World - Ben Counter, Marc Gascoigne A good, and rather violent, Warhammer 40K novel.
The Word Bearer Chaos Space Marines are on the hunt for one of their own who has gone rogue.
On the planet Torvendis, the barbarian tribes find common cause against the ruler, who has been sacrificing them to her god.
As the followers of different gods clash, who will end up in control?

Good action, with a few twists in it to keep you guessing.