Ring of Ascent is a unique item that can be found as Loot.
The Ring of Ascent is used as part of the Radial Equipment Menu, which is opened by pressing F (by default). It displays any ring equipped onto the player (in red tab) as well as rings in their inventory (in green tab); this ring can be both equipped and 'unquipped' with a left click. This allows for easy management of ring equipping; however, note that only one ring can be applied at a time.
When equipped, it will allow the player to hover about two to four blocks above a block surface and fly around at a decent speed; this mode can be toggled by double-tapping jump (Space by default). It will also negate fall damage and slow falling speed when toggled on. At the same time, it will drain the player's experience level while doing this, and will cease to work after consuming all of their experience. While active, a small tornado of leaves will swirl below the player's feet as an added visual effect.
Unlike other rings, the Ring of Ascent does not have a charge level that needs to be replenished by experience manually; rather, it draws directly from the experience bar itself over time.