Here is the full list of all 21 Before the Echo achievements. It takes around 10-12 hours to unlock all of the achievements on Windows.
See the hidden ending.
Learn all spells.
Synthesize Iridium.
Synthesize every recipe in the game.
Beat the game on any difficulty.
Defeat an enemy on the seventh floor using only Arclight.
Trigger Boost a Trigger Boost.
Obtain every droppable item in the game at least once.
Discover the name of she who controls fate.
While learning a spell, achieve 100% accuracy for the entire song.
Get her back.
Defeat an enemy within eleven seconds.
Queue up five spells in a row.
Defeat an enemy using only poison spells.
Recover over 150 mana in a single battle, and win.
Obtain all three droppable items from any single enemy.
Successfully complete a synthesis at 25% odds of success or lower.
Defeat an enemy with less than one second remaining on the clock.
Defeat the Holiday Whompa.
Complete a battle without failing a spell.
Successfully defeat your first enemy.