Here is the full list of all 30 Mortal Sin achievements.
Complete Cave C
Complete the Maw of Sin
Complete Dungeon C
Complete Forest B
Complete Forest A
Complete Forest C
Complete Dungeon B
Complete Cave A
Complete Cave B
Complete Dungeon A
Complete Dungeon A on Path of Torment difficulty
Complete Dungeon B on Path of Torment difficulty
Complete Dungeon C on Path of Torment difficulty
Complete Cave A on Path of Torment difficulty
Complete Cave B on Path of Torment difficulty
Complete Cave C on Path of Torment difficulty
Complete Forest A on Path of Torment difficulty
Complete Forest B on Path of Torment difficulty
Complete Forest C on Path of Torment difficulty
Complete the Maw of Sin on Path of Torment difficulty
Complete the Trial of Resolve
Complete the Trial of Resolve on Path of Torment difficulty
Complete Path of Absolution 5
Complete Path of Absolution 10
Complete Path of Absolution 15
Complete Path of Absolution 20
Complete Path of Torment 5
Complete Path of Torment 10
Complete Path of Torment 15
Complete Path of Torment 20