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