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.
Discover the name of she who controls fate.
Defeat an enemy with less than one second remaining on the clock.
Defeat an enemy on the seventh floor using only Arclight.
See the hidden ending.
Trigger Boost a Trigger Boost.
Queue up five spells in a row.
Learn all spells.
Synthesize every recipe in the game.
Synthesize Iridium.
Obtain every droppable item in the game at least once.
Beat the game on any difficulty.
While learning a spell, achieve 100% accuracy for the entire song.
Defeat an enemy using only poison spells.
Defeat an enemy within eleven seconds.
Get her back.
Successfully complete a synthesis at 25% odds of success or lower.
Recover over 150 mana in a single battle, and win.
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.