Here is the full list of all 44 Mages Initiation: Reign of the Elements achievements.
Complete the game.
Defeat the Big Bad.
Both allies survive.
Complete the third trial.
Make a red delivery to the Greencaps.
Reject a dark deal.
Find all three "Tear" class brooches.
Acquire one of each drink type at the tavern.
Earn your third spells from the Sphere of Knowledge.
Complete the second trial.
No sacred avian was harmed.
Ele'port to each pillar stone location.
Return a borrowed item.
Win a hand of Demon's Deal.
Kill 100 enemies.
Beat both Mage sparring partners.
Earn your second spells from the Sphere of Knowledge.
Complete the first trial.
Spare a tainted life.
Kill 50 enemies.
Earn your first spells from the Sphere of Knowledge.
Win the maximum number of Demon's Deal rounds.
Pick all mushroom clusters in the forest.
Optimally complete the Fire side quest.
Optimally complete the Water side quest.
Optimally complete the Earth side quest.
Optimally complete the Air side quest.
Complete all class-based side quests with optimal outcomes.
Complete the severed circle story branch.
Kill one of each monster type.
Find and read all books and notes.
Extinguish the Redcaps' camp fire.
An ally survives.
Max out all your stats.
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 Water 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).