Bone Spikes (Necrograft)

In a laborious procedure, you graft onto your body a number of wicked bone spikes that you can fire like needles and afterward regrow.  You can deal piercing damage with your unarmed strikes.  This spell and the abilities it grants can't be used while you are wearing heavy armor.

Whether you have to make Medicine checks to perform the surgery and whether you had to go on a quest to acquire the bone spikes, are details best left up to your GM.

You can expend a spell slot to activate the necrograft.  The more powerful the spell slot is, the more powerful the necrograft is.  When you expend a spell slot, the necrograft is active for 24 hours or until you finish a long rest, whichever comes first.  If you are a warlock, any spell slot that you expend to cast this spell is not regained until you finish a long rest.

The necrograft has four different power levels: Stage 1, Stage 2, Stage 3, and the most powerful, Stage 4.  The benefits are cumulative, if you activate the necrograft at Stage 2, you also gain the benefits described in Stage 1.  The DC of any features gained through this necrograft is your spell DC.

Activating the necrograft at Stage 1 requires expending a spell slot of at least 3rd level.

Activating the necrograft at Stage 2 requires expending a spell slot of at least 5th level.

Activating the necrograft at Stage 3 requires expending a spell slot of at least 7th level. 

Activating the necrograft at Stage 4 requires expending a 9th level spell slot.

At any given time, you can have up to four necrografts active.  One cannot exceed Stage 1, one can be up to Stage 2, one can be up to Stage 3, and one can be up to Stage 4.

This spell was originally designed as part of the Necrografter class, which can be found on DnDBeyond. It is intended to be used with the spell Unhallowed Arts, which can also be found on DnDBeyond.

Stage 1

You can fire up to 15 bone spikes between rests. They now have a range of 60 feet.  Despite being a ranged attack, you may add your Strength modifier instead of your Dexterity modifier to the attack and damage rolls. The bone spikes deal piercing damage equal to your unarmed strike damage. When you use the Attack action to use Bone Spikes, as a bonus action, you can fire a second bone spike as long as you are not wielding a shield.  If you have the Extra Attack feature or have cast Unhallowed Arts at a 3rd level or higher slot, you can fire two bone spikes as an action and a third as a bonus action if you are not wielding a shield/

Stage 2

Your bones spikes also threaten those who get too close to you.  You gain the Impaling Revenge ability.  If a creature hits you with a melee attack, you can immediately use your reaction to make an unarmed melee attack against that creature.  The damage is piercing.  Using this ability counts as one of your Bone Spikes uses.

You can fire up to 20 bone spikes between rests. 

When firing your bone spikes as ranged attacks, the range is now 90 feet.

Stage 3

Your numerous spikes can help you hold onto surfaces.  You can spend a Bone Spikes use as a reaction to reroll any Strength and Dexterity checks and saving throws to avoid being shoved, Strength (Athletics) checks to climb, and Dexterity (Acrobatics) checks and Dexterity saving throws to avoid slipping and take the higher result.  If you rolled with advantage, reroll only one of the dice.

You can now use Impaling Revenge when a creature misses you with a melee attack.

You can fire up to 25 bone spikes between rests.

When firing your bone spikes as ranged attacks, the range is now 120 feet.

Stage 4

You can now fire up to 30 bone spikes between rests.

You gain the Osteo-Impalement ability.  You can spend your action to rapidly regrow all of your expended bone spikes and then fire them all in a ferocious burst around you once per day.  You can angle the spines to affect a desired area.  Each time you use this ability, it can either affect all creatures adjacent to you, all creatures within 10 feet of you, creatures within 15 feet of you, or all creatures within 20 feet of you.  All affected creatures must make a Dexterity saving throw and take 10d8 piercing damage on a failed save or half on a successful save.  Like your unarmed strikes, this damage counts as from a magical weapon.  If you have the Elemental Cadaver necrograft, you can use Elemental Surge to increase this damage. 

After you use this ability, all of your bone spikes regrow, up to the maximum of 30.  Once you use this feature, you can’t use it again until you finish a long rest.

When firing your bone spikes as ranged attacks, the range is now 150 feet.

Additionally, you can use Impaling Revenge as a ranged retaliation.  After a creature hits you with an attack, misses you with an attack, or forces you to make a saving throw, you can use your reaction to immediately fire a bone spike at it.

Other necrografts can be found on DnDBeyond.  Here is the complete list:

Abomination Gut: You can vomit acid and belch poison.

Bonemail: You can better protect yourself and your allies.

Bone Spikes: You gain long-range attacks and can retaliate against foes.

Elemental Cadaver: You can channel fire, frost, or lightning.

Ghoul Claws: You can gouge and paralyze your foes as well as swim through the ground.

Mummified Eye: You gain a fearsome gaze, bonuses to initiative, and access to some divination spells. 

Lich’s Skull: You heighten your mental defenses and gain minor spellcasting plus knowledge.

Paladin’s Tomb: You’re the opposite of a holy man, but you can fight like one.

Two Corpses in One Grave: Sharing your body with another soul, you can change your appearance and shock your opponents with a hideous metamorphosis.

Wight Heart: Your attacks deal extra damage and can weaken your enemies.

Vampiric Grace: You can move fast, crawl on walls, and drink the blood of your foes.