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