Here is the full list of all 17 After Death achievements.
Finish the game with 100%
Kill the real final boss
Find all secret rooms
Find one of the masks
Kill the final boss
Meet all lost souls
Open the Gate
Activate all levers
Kill 50 enemies without any damage
Kill 10 enemies with only one scythe
Destroy 50 projectiles with armor powers
Kill half of bosses
Get the Fire armor
Get the Ice armor
Get your first item from Ignaro
Finish the game with less than 50%
Finish the game in less than 2 hours