Elren's Song of Seasons

You play a song laced with the magic of aggression, giving, lethargy or energy. When you cast this spell, choose one of the seasons: Summer, Autumn, Winter or Spring. You designate up to 6 creatures in range to be affected. Each creature affected must make a wisdom saving throw or fall under one of the effects listed below. A creature can choose to willingly fail the saving throw. As long as creatures can hear the music of the song they are affected, regardless if they move outside of the spells radius. Deafened creatures cannot be affected by the spell.

• Summer. Each target takes 2d6 fire damage on a failed save, increasing by 1d6 each subsequent round. On round 4 each target still under the effects of the song gains 2 exhaustion points
• Autumn. Each target gains 1d4 temporary hit points, increasing by 1d4 each subsequent round. On round 4, each target gains advantage on attack rolls, ability checks, and saving throws until the end of your next turn.
• Winter. Each target’s movement speed is reduced by 5, further decreasing by 5 each subsequent round. On round 4, each target still under the effects of the song become frightened, and cannot use reactions until the spell ends.
• Spring. Each target’s movement speed is increased by 5, further increasing by 5 each subsequent round. On round 4, each creature can use their reaction to do one of the following: Dash, Hide, Use an object, Use a magic item, Make a weapon attack, or cast a cantrip.

As a bonus action on each of your turns you can continue to play the song, causing each target affected by the spell to make another saving throw. The spell ends on a creature who succeeds on the saving throw. A creature who succeeds on a saving throw against this spell cannot be affected by it again until the spell has been casted again. The song ends if you do not use your bonus action in this way. 

When you cast this spell using a 5th level spell slot, you can play two of the seasons at once. When you cast it using a 7th level spell slot, you can play three of the seasons at once. When you cast it using a 9th level spell slot, you can play all 4 seasons at once.