Here is the full list of all 32 The Metronomicon: Slay The Dance Floor achievements.
Attain a 100 note streak.
Destroy the Speyeder of the Wild Forest.
Dethrone the Wraith King in the Haunted Kingdom.
End the dancing of a great Candy Dragon.
Decompile a fearsome Dance-o-bot.
Save the world of Koras from Dancemageddon.
Conquer one challenge in the school arena.
Make five arena challenges your chump
Beat the final challenge's omega boss.
Defeat every arena challenge.
Defeat every arena challenge on hard.
Succeed in your first story sidequest.
Succeed in beating five sidequests.
Unlock your first bonus song.
Survive your first 10 songs in Story Mode.
Survive every song in Story Mode.
Survive every song in Story Mode on Hard.
Perform your first upgrade to the school.
Unlock Sara's laboratory.
Purchase every ultimate weapon.
Succeed in every single sidequest.
Attain a 300 note streak.
Survive a story song without killing an enemy.
Survive a story song without healing any party member.
Apply six buffs to one hero at the same time.
Deal at least 5000 hp damage in one strike as Gwen.
Perform a perfect Solo-Lane Team Attack.
Perform a perfect meteor attack counter.
Kill five enemies in a row with a single attack.
Beat a fifty song playlist without ever pausing.