All death knights possess some knowledge of the power of runes, enough to empower their chosen school of dark arts. Some however choose not to become acolytes of these disciplines and instead focus on the power of runes themselves. Known as runesmiths, these death knights are capable of inscribing and utilizing stronger runes than most.
Death Knight Level - Spells
3rd - Detect Magic, Identify
5th - Magic Weapon, Create Healthstone
9th - Dispel Magic, Elemental Weapon
17th - Circle of Power, Teleportation Circle
When you take this subclass at 3rd level, you gain proficiency in the Arcana skill and in Blacksmith's Tools if you did not already have proficiency.
Also at 3rd level, you can turn one of your rune weapons into a magic weapon, gaining a +1 bonus to attack and damage rolls made with that weapon. This bonus does not apply if the rune weapon is already a magic item with a bonus to attack and damage rolls. You can change which rune weapon is empowered this way when you finish a long rest.
Additionally at 3rd level, when you spend runic power dice to deal damage with rune strike, the extra damage is force instead of necrotic.
At 7th level, you learn how to invoke the power residing in your runeforged runes, gaining special effects. Once you invoke a particular rune, you cannot do so again until you finish a short rest. The effect produced depends on the type of rune:
You can invoke this rune as a bonus action. For 1 minute, the rune weapon deals an additional 1d4 fire damage on a hit. Against an undead target, the damage increases to 2d4 and is radiant damage instead.
You can invoke the rune as a bonus action to increase your Strength score by 2 for 10 minutes. This increase can cause your score to exceed 20, but not 30.
You can invoke the rune as a bonus action to enter a prophetic state for 1 minute or until you’re incapacitated. Until the state ends, when you or another creature you can see within 60 feet of you makes an attack roll, a saving throw, or an ability check, you can use your reaction to cause the roll to have advantage or disadvantage.
When you are targeted by a spell that affects you and only you, you can use your reaction to invoke the rune to cast Counterspell against it. The caster then must make a Wisdom save against your spell save DC or take 1d10 psychic damage per spell level of the spell they cast due to the mental backlash.
You can invoke the rune as a bonus action, gaining resistance to bludgeoning, piercing, and slashing damage for 1 minute.
You can invoke the rune as a bonus action to gain a fly speed equal to your movement speed for 1 minute. While this benefit is active, you can move through objects and creatures as if they were difficult terrain. You take 1d10 force damage if you end your turn inside an object.
At 11th level, the power of your rune weapon increases. The bonus added to attack and damage rolls increases to +2. In place of gaining a +2 bonus to attack and damage rolls, you may choose a second rune weapon to gain a +1 bonus.
Additionally, you can have two runeforged runes active at once. This stacks with the Greater Runeforging ability, allowing for three active runes at 18th level.
At 15th level, the bonus to attack and damage rolls provided by your Runic Empowerment increases to +3. You can choose to give a +2 bonus to one rune weapon and a +1 bonus to another instead.
Additionally, when a creature within melee range makes an attack against you and misses, you can use your reaction to make a melee attack against the attacker.
When you reach 20th level, you can invoke all of your runes (expended or not) to become a deadly runic warrior. As an action, gaining the following benefits for 1 minute:
You have resistance to all damage.
When you take the Attack action on your turn, you can make one additional attack as part of that action.
Your melee weapon attacks score a critical hit on a roll of 19 or 20 on the d20.
Once you use this feature, you can’t use it again until you finish a long rest.