If a creature weighing at least 0.1 lb falls a distance of 10 or more feet, they take 1d6 damage for every 10 feet that they fall up to a maximum of 20d6 and are rendered prone. This damage is typically mundane, but may have other types as specified by the GM depending on what the creature hits when they land.
If the fall was into water rather than on land, the falling creature instead takes no damage for the first 20 feet of their fall. The next 20 feet deal 1d4 per 10 foot increment. Afterwards, the damage returns to 1d6 per additional 10 feet up to a maximum of 2d4 + 18d6. A creature that ends their fall underwater is not rendered prone but instead begins suffocating.