Here is the full list of all 23 Space Hulk: Deathwing achievements.
Find all the relics
Learn Vortex of Doom
Complete Commandement branch
Destroy a door
Kill a Broodlord
Kill an hybrid psyker
Kill a Genestealer's assault strain
Kill a Genestealer's warrior strain
Kill a Genestealer's stalker strain
Learn Inferno
Kill 666 enemies
Hack a door
Use the Psygate
Complete Devotion branch
Complete Psy branch
Finish a chapter without using a Psygate
unlock all Librarian's capacities in multiplayer
unlock all Heavy weapon support's capacities in multiplayer
unlock all Apothecary's capacities in multiplayer
unlock all Tactical Terminator's capacities in multiplayer
Kill 10,000 enemies
Make 1111 assists
unlock all Assault Terminator's capacities in multiplayer