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