Longbow of the Sky Sentinel
Longbow, Rare (requires attunement)
It is very well-crafted with elvish designs. There are bits of mithral scrolling throughout the bow itself and platinum caps on the ends.
Once per long rest, the wielder can use a Storm Arrow, which splits the next arrow fired from the bow into three separate arrows. Each arrow that hits deals an extra 1d6 Lightning damage.
If a magical arrow is shot from the Longbow, the two additional arrows would not copy its effects. However, each arrow can trigger Hunter’s Mark damage independently.