Comments from the writer: We took quite a few passes at the Osteomancer from Dragon Compendium before settling on this send up for fighter with more than a little Wolverine in its DNA. Use your Hit Dice to empower your strikes as you grow weapons from your very body! This is the most up-to-date version of the subclass as it appears in Valda’s Spire of Secrets.
A bone knight, or an osteoth, is a warrior that has undergone an agonizing transmutation ritual, granting them the ability to fully control their bones. While this power is plainly disfiguring, it allows them to grow bone protrusions for weapons and armor, changing their skeleton’s size and shape at will. Mastering this ability is a feat of endurance and creativity, resulting in a fighter whose most powerful weapon is not sheathed at their side, but sheathed within their flesh.
Many fighters believe the osteoth ritual is a mere myth, a flight of fancy traded around campfires. And yet, the process is indeed real, preserved among moldering tomes and in the minds of deranged wizards. With some resourcefulness, the procedure can be replicated with the contents of any alchemist’s lab, with a generous fatality rate of nearly half.
Adamant Ivory
Starting when you choose this archetype at 3rd level, you can sprout boney plates from your skin. While you aren’t wearing armor, this natural armor provides you a base AC of 17 (your Dexterity modifier doesn’t affect this number). You can use your natural armor to determine your AC if the armor you wear would leave you with a lower AC. A shield’s benefits apply as normal while you use your natural armor.
Additionally, when you take bludgeoning, piercing, or slashing damage, you can use your reaction to shield yourself from harm. Expend a Hit Die, roll it, and decrease the damage taken by the number rolled.
Adamant Ivory
| Fighter Level | Armor Class |
| 3rd | 17 |
| 5th | 18 |
| 10th | 19 |
| 18th | 20 |
Bone Blades
Also at 3rd level, you can sprout blades of jagged bone from each of your palms or wrists as you would draw a weapon. These bone weapons have your choice of the statistics of a longsword, shortsword, or scimitar. You can’t be disarmed of these weapons. You can retract these weapons as you would sheathe a weapon.
Starting at 7th level, your blades are considered magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage. Additionally, once per turn when you hit a creature with a bone weapon, you can expend a Hit Die to extend the bone into the target. Add the Hit Die and your Constitution modifier to the weapon’s damage roll.
Hardy Constitution
By 7th level, your bones and their marrow have grown more robust, granting you a formidable healing factor. You regain all of your expended Hit Dice, rather than half of them, when you finish a long rest.
Restrucure
Starting at 10th level, you can shift your skeletal structure as an action to transform your appearance. When you do so, you determine the specifics of the changes, including adjusting your height and weight, the shape of your face, the presence or absence of your teeth, your posture, and so on. You can even change your size
from Medium to Small or vice versa. The extent of these changes only extends to your bone structure: you can’t change your skin color, hair length, or clothing using this ability.
Improved Ivory
By 15th level, your bones are as hard as steel and as pliant as copper. When you expend a Hit Die to use your Adamant Ivory feature to reduce damage or use your Bone Blades feature to deal additional damage, you can expend two Hit Dice at once. You subtract the total from the bludgeoning, piercing, or slashing damage you take, or add the total and your Constitution modifier to the weapon’s damage roll, respectively.
Master Osteoth
Starting at 18th level, when you roll initiative and have fewer than half your Hit Dice, you regain 1d6 Hit Dice.
Additionally, on your turn, you can expend 3 Hit Dice to regain a use of your Second Wind feature, or expend 8 Hit Dice to regain a use of your Action Surge feature (no action required).
