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