[Necromancy] Weapon - Osteocast

Once wielded by the Shattered King and leader of the Horde of Bone, this bow now rests forgotten in the mires of the Necrosheer Wastes. Warm bloody marrow ooze from the bow's pale spurs, protected for centuries by the material's preservation instincts. The spurs seem to twitch and bend toward any living creature that approaches it.

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Osteocast
Weapon (longbow), legendary (requires attunement)

You must spend the duration of the attunement period holding this bow, during which you absorb the bow into your body. If you don’t normally have bones, the bow grows some for you. Once attuned, you cannot be disarmed of the bow, and you sprout spines and horns from your body, granting you the Natural Weapons benefit of an alter self spell.

Osseus Bow. You can use an action to painfully summon the bow from your body or dismiss it back into your body. You also have a +1 bonus to attack and damage rolls made with this magic weapon. Immediately before you make a ranged attack with this weapon, the bow produces a shard of bone for you to use as ammunition.

Osteomancy. This weapon has 5 charges for the effects listed below. You must expend the necessary number of charges to use an effect; if an effect imposes a saving throw, the DC is 17. The bow regains 1d4+1 expended charges daily at dusk.

• Bone Spikes (1 charge). As an action, you can fire an arrow at a point within 150 feet of you, no attack roll required, and cast spike growth centered on that point. This spell summons bone spears instead of plants and damage can't break your concentration on this spell.
• Ossify (1 charge). Immediately after you hit a humanoid with an arrow fired from the bow, you can use a bonus action to cast hold person on the target.
• Armor of Bone (2 charges). As an action, you transform bone into makeshift armor. For the next hour, you have resistance to nonmagical bludgeoning, piercing, and slashing damage.
• Legion of Bone (3 charges). As an action, you can fire an arrow at a point within 150 feet of you, no attack roll required. A burst of necromantic energy sweeps out from that point out to 10 feet in all directions. Within that area, each dead creature of CR 1 or lower that has bones rises as a skeletal version of its former self. In combat, your skeletal minions take their turns immediately after yours and obey your commands to the best of their ability. They use their original statistics with the following changes: it is undead; it has vulnerability to bludgeoning damage; it has immunity to poison damage and cannot be exhausted or poisoned; any damage it deals that isn't bludgeoning, piercing, or slashing it deals becomes magical piercing damage, manifesting as bone. Each skeletal minion lasts for 1 hour or until it dies.

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DESIGN COMMENTARY

This bow is designed to fill a couple niches - I wanted something bone-related for the theme, as well as a magic bow, which is quite uncommon in the game (plus I need practice drawing bows). Interestingly, a lot of "ostemoancy" falls under "biomancy," which tends to fall under transmutation, so I was ended up creating effects first and finding analogue spells to reflavor. Armor of Bone was almost Boneskin (reflavored stoneskin), which would have sounded really dumb.

Legion of Bone is meant to call to the Shattered King's role as an army leader of skeletons. It's usable at most once per day and summons several minions for assistance. Though powerful because of 5e's bounded accuracy design, the minions must be CR 1 or lower, which at least limits the availability of this option.

For the art, I studied a couple bone-related references, like the animal spine for the grip, the spiraling antelope horns for the arms, and a stretchy ligament for the string. The coloration started out a little messy but I think pulled together. It's just a little hard to read silhouette-wise well because of how thin a bow is.