The rules on "Falling" state:
[...] At the end of a fall, a creature takes 1d6 bludgeoning damage for every 10 feet it fell, to a maximum of 20d6...
When looking at the reverse gravity spell I realized it states:
[...] If some solid object (such as a ceiling) is encountered in this fall, falling objects and creatures strike it just as they would during a normal downward fall...
And then in this related question "Do any damage resistances apply to Reverse Gravity?" it is shown that falling damage, even from this spell, is still just bludgeoning damage. Is there any way to change the type of damage that a fall inflicts?
Maybe some object explicitly has this property or there is a way to change all damage a creature takes to another type, which would thus include fall damage?
If this is possible, then certain creatures, like the treant, would take more damage from falling so pushing them off a cliff or using reverse gravity on them would be more effective.
If a method is available to both PC's and Monsters, that would be ideal. But if there is a method only available to PC's and another method only available to Monsters that would work as well. If these should be separate questions, that would be alright.
The closest thing I've found is the Horizon Walker Ranger's Planar Warrior feature, though it only works on weapon attacks and so not fall damage; the feature states:
[...] As a bonus action, choose one creature you can see within 30 feet of you. The next time you hit that creature on this turn with a weapon attack, all damage dealt by the attack becomes force damage, [...]
