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.
Defeat an enemy on the seventh floor using only Arclight.
Get her back.
Defeat an enemy within eleven seconds.
Queue up five spells in a row.
Recover over 150 mana in a single battle, and win.
While learning a spell, achieve 100% accuracy for the entire song.
Trigger Boost a Trigger Boost.
Defeat an enemy with less than one second remaining on the clock.
Defeat an enemy using only poison spells.
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.
Successfully defeat your first enemy.