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.
Beat the game on any difficulty.
Trigger Boost a Trigger Boost.
Defeat an enemy using only poison spells.
Queue up five spells in a row.
Get her back.
Defeat an enemy within eleven seconds.
Successfully complete a synthesis at 25% odds of success or lower.
Recover over 150 mana in a single battle, and win.
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.
Successfully defeat your first enemy.
Complete a battle without failing a spell.
Synthesize Iridium.
See the hidden ending.
Learn all spells.
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.
Synthesize every recipe in the game.