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