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