The Onion Ring, while is accurate to its in-game description, doesn't exactly behave as one would expect. The Onion while held in the offhand will guarantee an arrow hits a target, rather than the arrow finding a target the player is trying to attack, the arrow instead immediately hits the player. This makes the Onion Ring more of a joke item rather than anything practical and worth using.
The Onion Ring belongs to the Aqua collection and does have a prerequisite to unlock it's recipe. This prerequisite demands the player that they must play for 1000 minutes, or 16 hours and 40 minutes. The Onion Ring has a cheap cost to craft requiring:
Due to the arrow immediately hitting the player upon being shot, the Onion Ring allows players to stand inside end crystals, shoot their arrows, and not cause it to explode.
Arrows shot with the Onion Ring will always hit the player no matter how much the bow is charged.
Arrows shot with the Onion Ring retain all arrow properties (tipped/spectral) and all bow properties (ie. punch) when hitting the player.
The Onion Ring when combined with the Hoshiyumi can lead to some interesting mobility possibilities. The Player can launched themselves into the air a significant distance with just these two. With an elytra, the Hoshiyumi and Onion Ring can allow the player to perform midflight jumps.
For whatever reason the player may have arrows with potion effects, the Onion Ring may be used to have those effects applied to the player.