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