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