The Knave (Martial Archetype)
The Knave steeps themselves in strong emotions for their power, tapping into dark power fueled by all manner of sentiment, from compassion toward a friend or loved one to scorn for an enemy.
Whatever the source, these powers manifest as the negative energies which fuel a Knave's assault, augmenting their attacks and bolstering the defenses of themselves and their allies with solemn darkness.
Dark Fervor
When you adopt this Archetype at 3rd level, you tap into a wellspring of energy deep in the center of your being. This wellspring is represented by your Dark Fervor dice, the starting size of which is a d6. You have a number of these dice equal to half your proficiency bonus, and they fuel the various powers you have, which are detailed below.
Changing the Die's Size. Whenever you use a power that requires you to roll one or more of your Dark Fervor dice of the same size, they decrease by one size after the roll. This represents the wellspring drying up. For example, when you use a power that requires you to roll a Dark Fervor die and you roll a d6, it becomes a d4. If you use a power and roll a d4, that die becomes unusable until you finish a short rest, which restores one expended die to its starting size.
Some of your powers require creatures to make a saving throw against their effects, the DC of which equals 8 plus your proficiency bonus plus your Charisma modifier.
Whenever you finish a long rest, your Dark Fervor dice reset to their starting size. When you reach certain levels in this class, the starting size of your Dark Fervor dice increases: at 5th level (d8), 11th level (d10), and 17th level (d12).
The powers below use your Dark Fervor dice.
Grim Cleaver. When you take the attack action on your turn, you can use up to two Dark Fervor dice of the same size to cause one of your attacks to deal additional necrotic damage equal to the number rolled.
Solemn Shield. As a bonus action, you can use one or more Dark Fervor dice of the same size to grant a number of creatures equal to your Charisma modifier within 30 feet that you can see temporary hit points equal to the number rolled plus your fighter level.
Steely Determination
Sarting at 7th level, your force of will invigorates the font of darkness inside you. Whenever you use your Indomitable feature to reroll a saving throw, your unexpended Dark Fervor dice increase by one size up to their starting size.
Dire Ardor
By 10th level, your ability to control your emotions grows more intricate, and as a result, your powers improve in the following ways:
Grim Cleaver. The target must make a Wisdom saving throw, on a failed save, the target has disadvantage on attack rolls made against targets other than you until the end of your next turn. A creature is immune to this feature if it is immune to being frightened.
Solemn Shield. Each creature of your choice additionally gains a bonus to their Armor Class equal to half your Proficiency Bonus until it loses all of its temporary hit points.
In Addition, you gain the following power:
Grave Recovery. When you use your Second Wind feature, you can use one or more Dark Fervor dice of the same size, rolling them and adding the number rolled to the total.
To the Hilt
At 15th level, the chill of death infuses your attacks with a demented ferocity. When you take the attack action on your turn with no more than half your hit points remaining, you can choose to make one of your attacks with disadvantage. A hit scored with this attack is a critical hit.
You also gain the following powers:
Scathing Rend. As an action, you can use one of your Dark Fervor dice to hurl a bolt of dark energy at a creature you can see within 30 feet. Make a ranged spell attack against the creature (Spell Attack modifier = Proficiency Bonus + Charisma modifier). On a hit, the creature takes necrotic damage equal to the number rolled.
Hateful Surge. As an action, you can use one or more Dark Fervor dice of the same size to unleash a wave of hate-fueled necrotic energy that emanates from you. Each creature of your choice within 15 feet of you must succeed on a Wisdom saving throw or take necrotic damage equal to the number rolled, or half as much damage on a successful save. If a creature that fails its saving throw is frightened of you, its speed is reduced by half until the end of your next turn.
Macabre Furor
At 18th level, you reach the deepest part of your inner shadow, availing yourself of its energy for a brief moment. When you use your Action Surge, using your powers does not decrease the size of your Dark Fervor dice until the end of your next turn.
Additionally, you gain the following power:
Mortal Paroxym. If you take damage that reduces you to 0 hit points, you can use your reaction to expend one of your Dark Fervor dice to delay falling unconscious until the end of your next turn. You still must make death saving throws, and you suffer the normal effects of taking damage while at 0 hit points. However, if you would die due to failing death saving throws, you don't die until the end of your next turn, and you die then only if you still have 0 hit points.