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