The pink Villager's Timber represents Hilda, a young pink-haired woman who uses an axe in battle.
The yellow Byleth minion represents Claude, the leader of the Golden Deer house, whom Hilda serves as his unofficial retainer.
The stage features Lorenz as a background character, referencing Hilda's affiliation with the Golden Deer house in Fire Emblem: Three Houses.
The Attack Power ↑ rule references the massive growth rate of Hilda's stats during the timeskip in Three Houses.
Other trivia:
This spirit's Support type references Hilda's role as a member of Byleth's party in the Verdant Wind route of Three Houses.
This spirit's Critical-Health Attack ↑ ability further references the massive growth rate of Hilda's stats during the timeskip in Three Houses.