Here is the full list of all 51 Shadowcrawl achievements.
Spoke with the Goblin Engineer
Found And Killed the Shogoth In The Monolith Of Shadows
Cleared Floor 5 of the NEXUS, but it only gets harder from here
Earned the secret title "Mage"
Killed Holy Knight Renaud
Joined the "Sect of the Hallowed" covenant
Joined the "Dirge of the Hollowed" covenant
Joined the "Dirge of the Unholy Blood" covenant
Joined "Cult of Shadows" covenant
Joined "Servants of the Blood" covenant
Joined the "Sect of Holy Blood" covenant
Joined "Holy Hounds" covenant
Joined "NULL R3F3R3NCE" covenant
Joined "Order of the Yellow Sign" covenant
Earn the secret title, "Light"
Earn the secret title, "Husk"
Earned the secret title "Hollow"
Earn the secret title, "Savior"
Earn the secret title, "Assassin"
Earn the secret title, "Sangromancer"
Earn the secret title, "Thrall"
Earn the secret title, "Flame"
Kill Yellow King Hastur
Traded with the Trogloth Knight
Traded with the Human Engineer
Return the Orcs to their true form
Trade with the Nin Ghost
Traded with Human Ghost
Assist Trog Engineer
Assist the Goblin Knight
Assist the Nin Knight
Kill The Void Walker
Killed Loki, the Goblin God
Killed Holy Knight Icabod
Killed Bed of the Deathcaps
Killed Holy Knight Alaric
Helped Tlacelel burn the Grave of the Liches
Killed Holy Knight Hilde
Hacked the Murder Oak
Killed Holy Knight Euric
Destroyed the central A.I. unit of the Peace Keepers faction of robots
Helped Stan complete the Dark Ritual.... uh-oh
Killed Shub-Nugurath in the Forest of the Black Goat
Helped Zasset the Undead find more machine parts
Kill the Demon Michael Davies
Helped Miya the Lady of Blades to a Portal
Helped Rsi the Trogloth Ghost repair her Stealth Module.
Helped Celel the Nyn Engineer to a Portal
Began worshipping the Demon Michael
Began worshipping the Undying Meat
Killed the Butcher