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