I imagine Autumnal Damage would be similar to winter arriving in Bone, but with falling leaves.
Can someone explain?
They entered into fall, so the bard prevented fall damage by using feather fall.
Another word for the season of Autumn is Fall.
Thus, the DM is about to make a pun about Fall damage. The player of the bard notices the incoming pun, takes defensive action via casting a counter-pun spell, and thus prevents a table full of groaning and moaning, and possibly even laughter.
Laughter from a pun like this is a rare thing, a charisma check of 19 with disadvantage.
DM: Instead of leaves, the forest is covered in what appears to be goose down.
Are we about to roll initiative against grass??
Leaves fall, everyone dies