Oath of the Doomslayer

The Oath of the Doomslayer is for Paladins who have a burning hatred for all things unholy. Whether it was a need for vengeance, or divine ordainment, those who take this Oath are forevermore bound to an endless crusade against the unnatural creatures from beyond the veil. They cannot, and will not cease until all the lands are rid of these devils and their corrupting influence.

Many who take this Oath follow a god of morally good, or at the very least not out-right evil, alignment who for one reason or another seeks the destruction of the damned. These Paladins wear thick plate armor that has been singed by fire and chipped by talons, often while carrying menacing looking weapons.

These Paladins share the following tents:

• Protect the pure and innocent from the scourge of the unholy.
• The most sacred form of worship is wetting one's blade with the blood of the damned.
• Rip and tear until evil is no more.

Inspired by the Doom videogame franchise :P

Level 3: Oath of the Doomslayer Spells

The magic of your oath ensures you always have certain spells ready; when you reach a Paladin level specified in the Oath of the Doomslayer Spells table, you thereafter always have the listed spells prepared.

Paladin Level	Spells
3	Jump, Hunter's Mark
5	Shatter, Enhance Ability
9	Fear, Counterspell
13	Freedom of Movement, Fire Shield
17	Commune, Teleportation Circle

Level 3: Doomblade

As a Bonus Action, you expend a use of your Channel Divinity to transform any Martial Weapon you are proficient with into a Doomblade: A Greatsword with a blade of pure, Fiend killing energy. 

Doomblade: Greatsword, 2d6 + your Strength Modifier of Slashing damage as well as Radiant damage equal to your Charisma Modifier.

It has the "Heavy" and "Two-Handed" Weapon Properties, but not the Weapon Mastery. The Doomblade counts as a Magic Weapon for the means of overcoming Resistances.

The Doomblade has 3 Charges per use of Channel Divinity. Every time it successfully hits a creature, it expends a Charge. Once all Charges are spent, the Doomblade reverts back to its original form. However, it can remain active longer if fed with the blood of the unholy. The first successful attack against a Fiend, Undead, or Aberration type creature with the Doomblade does not count towards the Charges, but every subsequent attack against the same creature does.

You can revert the Doomblade back to its original form early (no action required). It also reverts back if you are disarmed.

At Higher Levels: You gain one additional Charge for the Doomblade when you reach Paladin Levels 5, 9, and 13.

Firearms Rule: If you are in a campaign with Firearms in it, you will also gain Proficiency with them at this Level. 

Level 7: Aura of Rage

When surrounded by the damned, you and your allies gain an attack bonus while in your Aura of Protection.

For every Fiend, Undead, or Aberration creature that is within your Aura of Protection, you and your allies gain a +1 on attack rolls per creature when targeting them with a melee attack. The bonus is not applied to creatures that are not Fiends, Undead, or Aberrations within the Aura.

This bonus stacks up until it equals your Proficiency Bonus.

Example: At Level 6, you have a Proficiency Bonus of +3. If you have 4 Undead within your Aura and your ally (also within the Aura) attacks one of them, they get +3 on the attack roll. If one of the Undead dies, the bonus remains at +3 until another Undead dies and it drops to +2.

When Using Your Doomblade: On top of the attack bonus, the Doomblade also gains an equal bonus to the Radiant damage it deals. In the example above, the Doomblade would deal an additional +3 Radiant damage against the Undead until there were 2 left and then would drop to +2 Radiant.

Level 15: Rip and Tear

Sometimes, the best way to let out your anger is by placing your fist through a demon's skull... repeatedly.

Your Movement Speed increases by 10ft. and all Unarmed Strikes against Fiends, Undead, and Aberrations are made with Advantage.

This Subclass Feature upgrades your "Radiant Strikes" Paladin Class Feature by allowing you to choose whether your Unarmed Strikes deal Bludgeoning + Radiant damage, like normal, or replace the Bludgeoning with full Radiant damage.

Level 20: Berserk Mode

When you activate your Doomblade, you channel your rage and fury into the weapon, making it far deadlier than it already was. Using the standard Doomblade now grants you the "Graze" Weapon Mastery but the damage dealt by it equals both your Strength and Charisma Modifiers.

You can also now choose 3 additional options for how your Doomblade manifests. You can only choose one manifestation per use of Channel Divinity.

Doomblades. Your Doomblade takes the form of two Longswords, because what's better than one Doomblade if not a second?

Doomblades: Dual-wielded Longswords, 4d6 + your Strength Modifier of Slashing damage as well as Radiant damage equal to your Charisma Modifier.

Used just like the standard Doomblade, they strike together with each Attack they make (counting a single weapon even through they are two) and have the "Sap" Weapon Mastery.

Unlike the standard Doomblade, the first successful Attack against a Fiend, Undead, or Aberration type creature will still expend a Charge. However, killing a creature of these types with the Doomblades will replenish 1 Charge of your Doomblade (Up to the maximum of 6).

Fists of Exorcism. Your Doomblade takes the form of thick, spiked plate gauntlets imbued with the righteous power of your god.

Each time you take an Attack Action with the Fists of Exorcism, you expend 2 Charges of your Doomblade to use your "Extra Attack" Class Feature and make two Unarmed Strikes against a single enemy creature for 2d8 Bludgeoning damage + your Charisma Modifier of Radiant damage each. You can target a creature within 15ft. of you with the Strikes, lunging yourself toward them without using any of your Movement Speed.

If the creature is a Fiend, Undead, or Aberration type, a Charge will not be expended only if the first of the two Strikes hits. If the first Strike misses, both Charges will be used even if the second Strike hits. Further, if one of these types of creatures is reduced to 0 Hit Points with this Attack, you rip them in half and can immediately make the same Attack on another creature within range (still without using your Movement Speed) by expending 1 additional Charge if the creature died on the first of the Strikes or 2 additional Charges if they died on the second. You can continue chaining these Attacks this way until you run out of Charges.

Note: The Unarmed Strikes damage from the Fists of Exorcism cannot be changed by the "Rip and Tear" Subclass Feature nor do they gain additional Radiant damage from the "Radiant Strikes" Class Feature.

BFG: "Bringer of Fiends to God". Your Doomblade takes the form of a large Arbalest that hums with destructive energy.

Taking the Attack Action with the BFG uses both of your Attacks from your "Extra Attack" Class Feature and expends all Charges of your Doomblade for this use of Channel Divinity.

The BFG fires one large bolt of Radiant energy at one target that arcs out smaller Radiant energy bolts to up to 6 separate targets in sight within a 300ft. Cone in front of you.

Choose one target and make a Ranged Attack against them (as if you are making a melee attack with the Doomblade) for the large bolt. On hit, the bolt deals 5d10 Radiant damage. Regardless if the large bolt hits or not, the other targeted creatures must succeed a Charisma saving throw equal to your Spell Save DC as the smaller bolts strike them automatically. They take 2d10 Radiant damage on a failed save or half as much on a successful one. If the targeted creature is a Fiend, Undead, or Aberration type creature, they make the save with Disadvantage.

If the creature targeted with the large bolt is killed by it, a feedback loop will occur and deal an additional 1d10 Radiant damage to all other targeted creatures. This additional damage is not halved if the creature(s) succeeded the Charisma save.