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