Here is the full list of all 23 Space Hulk: Deathwing - there are Enhanced Edition achievements.
Complete the Devotion branch
Kill 10,000 enemies
Find all the major relics in the main campaign
Complete the Command branch
Complete the Psy branch
Learn Vortex of Doom
Learn Inferno
Finish a chapter in the main campaign without using a Psygate
Use the Psygate
Unlock all of the Apothecary's abilities in multiplayer
Unlock all Tactical Terminator abilities in multiplayer
Unlock all of the Librarian's capacities in multiplayer
Unlock all Assault Terminator's abilitiess in multiplayer
Unlock all of the Heavy Weapon Support's abilities in multiplayer
Perform 1,111 assists in multiplayer mode or the special missions
Kill 666 enemies
Destroy a door aboard the Olethros
Kill a Broodlord
Lock a door aboard the Olethros
Kill a scythe-strain Genestealer
Kill a stalker-strain Genestealer
Kill a warrior-strain Genestealer
Kill an hybrid psyker