The 羽落药水 is a 增益药水 which grants the 羽落 增益 when consumed. The buff slows the player's fall speed for 5 minutes and gives a bit of control of gravity to the player, allowing them to jump higher than normal. The buff lasts for 5 minutes, but can be cancelled at any time by right-clicking the icon.
The player can hold the ▼ 下 key to fall like normal in case of a rush, and the player can also hold the ▲ 上 key to slow their fall even further or jump ridiculous heights. While under the effects of both Featherfall Potion and 重力药水, holding the ▲ 上 key will make the player fall up at normal speed. The player will fall up at a slowed speed when holding no direction.
The effects of the Featherfall Potion can also be used to jump higher. By holding ▲ 上, grappling a 平台 above you, and releasing the grapple before it is complete, one may achieve jumping heights of several hundred blocks.
掉落伤害 is also negated, even when falling normally. It is worth noting that the Featherfall Potion also increases the distance players are knocked back when hit by an attack.