Here is the full list of all 14 Ceaseless Night achievements.
Kill Rat King
Kill Jeff the Bandit Captain
Kill Horrid Crawler
Kill Big Jelly
Kill Zombie Brute
Kill The Flesh
Kill Spider Queen
Kill Wraith Lord
Kill Dragon
Kill The Lich King
End the Ceaseless Night
Remain in Darkness
Have Each of the 19 Character Classes at Camp
Unlock all 50 Trinkets