Here is the full list of all 22 Divinus Vanitas achievements.
Kill 10 Outsiders
Kill 100 Outsiders
Kill 1000 Outsiders
Kill 10 Barghests
Kill 100 Barghests
Kill 1000 Barghests
Kill 5 Centaurs
Kill 50 Centaurs
Kill 500 Centaurs
Kill the dragon
Obtain all spells
Obtain all unique equipment
Explore all major regions
Fireballs are very dangerous...
Play with two others for a while
Defeat another player
Explore the floating rocks
Collect items of the past
Clear the 5th iteration
Clear the 2nd iteration
Learn the truth
Reach level 20