Here is the full list of all 26 Legend of the Tetrarchs achievements worth 1,000 gamerscore.
Bought 40 types of items.
Completed 20 story quests.
Dealt more than 10000 damage in one blow.
Obtained 30 types of Carmina.
Completed 15 story quests.
Defeated 10 quest monsters.
Defeated 1000 enemies.
Strengthened 40 types of equipment up to +5.
Bought 10 types of items.
Completed 10 story quests.
Defeated 300 enemies.
Obtained 10 types of Carmina.
Strengthened 10 types of equipment up to +5.
Dealt more than 1000 damage in one blow.
Completed 5 story quests.
Defeated 100 enemies.
Defeated 1 quest monster.
Obtained 1 type of Carmina.
Bought 1 type of item.
Strengthened 1 type of equipment up to +5.
Completed 25 story quests.
Completed 30 story quests.
Completed all story quests.
Dealt more than 50000 damage in one blow.
Defeated 20 quest monsters.
Achieved all quests.