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.
Defeat an enemy using only poison spells.
Discover the name of she who controls fate.
See the hidden ending.
Synthesize every recipe in the game.
Synthesize Iridium.
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.
Defeat an enemy within eleven seconds.
Queue up five spells in a row.
Get her back.
Trigger Boost a Trigger Boost.
While learning a spell, achieve 100% accuracy for the entire song.
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.
Complete a battle without failing a spell.
Successfully defeat your first enemy.