Here is the full list of all 44 Mages Initiation: Reign of the Elements achievements.
Complete the game.
Defeat the Big Bad.
Max out all your stats.
Both allies survive.
An ally survives.
Complete the third trial.
Earn all Water class Bonus points.
Make a red delivery to the Greencaps.
Reject a dark deal.
Extinguish the Redcaps' camp fire.
Find all three "Tear" class brooches.
Earn your third spells from the Sphere of Knowledge.
Complete the severed circle story branch.
Complete the second trial.
No sacred avian was harmed.
Ele'port to each pillar stone location.
Return a borrowed item.
Kill 100 enemies.
Optimally complete the Water side quest.
Earn your second spells from the Sphere of Knowledge.
Complete the first trial.
Spare a tainted life.
Kill 50 enemies.
Acquire one of each drink type at the tavern.
Pick all mushroom clusters in the forest.
Win a hand of Demon's Deal.
Beat both Mage sparring partners.
Earn your first spells from the Sphere of Knowledge.
Win the maximum number of Demon's Deal rounds.
Optimally complete the Fire side quest.
Optimally complete the Earth side quest.
Optimally complete the Air side quest.
Complete all class-based side quests with optimal outcomes.
Kill one of each monster type.
Find and read all books and notes.
Finish the game with max XP / score.
Finish the game with all 4 classes.
Kill only the bosses (no regular monsters).
Earn all Fire class Bonus points.
Earn all Earth class Bonus points.
Earn all Air class Bonus points.
Kill 500 enemies.
Kill 1,000 enemies.
Beat the game without equipping any extra gems or items (after the initial tutorial).