Featherfall

 is a Buff granted to the player upon consuming a Featherfall Potion. The buff slows the player's fall speed 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 down (S by default) key to fall like normal in case of a rush, and the player can also hold the up key (W by default) to slow their fall even further or jump ridiculous heights. While under the effects of both Featherfall and Gravitation, holding the up key will make the player fall up at normal speed. The player will fall up at a slowed speed when holding no direction.

Fall damage is also negated, even when falling normally. However, knockback from taking damage is increased.

Trivia

 * The icon for the buff bears a slight resemblance to the Cape Feather from Super Mario World.