So, let me preface I'm still quite new to DnD. But I've been playing as a Bard and I enjoy it, however after looking at the Level 4 spells I didn't really like any, so I am asking my DM if I can homebrew one and he said possibly. So this is what I've come up with so far.

Tempo Setter- Cast a Line of magical notes that are set to the tempo of your choice. Creatures that walk through this line must make a Wisdom saving throw, upon failing the creature is then set at that tempo until the spell ends.

Adagio- Creatures set at adagio have their movement reduced by 15 but lingering spells and effects they apply last for 2 additional turns.

Allegro- Creatures set to allegro have their movement increased by 15 but their lingering spells and effects last for 2 less turns.

Line Length- 20 feet. Line Height- 5 Feet. Costs 1 Action Concentration- 10 Turns.

This spell can be Upcasted at higher levels, for each level Upcast add 5 to the movement effect and 1 turn.