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