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