Base Class: Fighter
Your careful study of magic to augment your martial prowess has lead you down a dark path. The call of the abyss, necromancy and forbidden summoning's have pulled you away from your Eldritch Knight brethren and into something deeper, darker, and far more grim. You have focused your study on the necromantic and conjuration schools of magic, learning to embrace and shape death rather than fear it.
Grim Knight Spellcasting
When you reach 3rd level, you augment your martial prowess with the ability to cast spells.
Cantrips; You learn two cantrips of your choice from the following list: chill touch, spare the dying, thunderclap, ray of frost, and message. You learn an additional cantrip of your choice from this list at 10th level.
Spell Slots; The Grim Knight Spellcasting shows how many spell slots you have to cast your spells of 1st level and higher. To cast one of these spells, you must expend a slot of the spell's level or higher. You regain all expended spell slots when you finish a long rest.
Spellcasting Ability; Intelligence is your spellcasting ability for your necromancy and abjuration spells, since you learn your spells through study and memorization. You use your Intelligence whenever a spell refers to your spellcasting ability. In addition, you use your Intelligence modifier for the saving throw DC of a spell you cast and when making an attack roll.
Spell Save DC = 8 + your proficiency bonus + your intelligence modifier
Chill Touch
You learn the chill touch cantrip
Message
You learn the Message cantrip
Ray of Frost
You learn the Ray of Frost cantrip
Spare the Dying
You learn the Spare the Dying cantrip
Thunderclap
You learn the Thunderclap cantrip
Expanded Spell List
The Grim Knight archetype lets you choose from an expanded list of spells when you reach certain levels. The following spells are added to the necromancy spell list for you.
Fighter Level Spells
3rd Hellish Rebuke
5th Shield
7th See Invisibility
9th Find Steed
Weapon Bond
At 3rd level, you learn a ritual that creates a magical bond between yourself and one weapon. You perform the ritual over the course of 1 hour, which can be done during a short rest. The weapon must be within your reach throughout the ritual, at the conclusion of which you touch the weapon and forge the bond.
Once you have bonded a weapon to yourself, you can't be disarmed of that weapon unless you are incapacitated. If it is on the same plane of existence, you can summon that weapon as a bonus action on your turn, causing it to teleport instantly to your hand. You can have up to two bonded weapons, but can summon only one at a time with your bonus action. If you attempt to bond with a third weapon, you must break the bond with one of the other two.
Grim Harvest
At 3rd level, you gain the ability to reap life from enemies you kill with a weapon attack. Once per turn, when you kill a creature with a weapon attack, you gain temporary hit points equal to your Intelligence modifier.
Chain of Fate
At 7th level, your familiarity with death and the undead grants you resistance to necrotic damage. You also gain the Grim Knight ability Chain of Fate.
Chain of Fate; As a bonus action on your turn, you summon from the ground before you a spectral version of your bonded weapon trailing a long chain. The weapon spears into the ground at your feet, lashing out with the chain, targeting a creature of your choice within 30 feet. The creature must make a Dexterity saving throw against your spell save DC. On a failed save, the creature is wrapped in the chain, taking 1d8 necrotic damage and is pulled to the spectral weapon where it is grappled in place. On a successful save, the creature takes half damage and shrugs off the other effects of the chains.
A grappled creature may use its action to make a Strength check, versus your spell save DC, freeing itself on a success. Once freed, the spectral weapon and chains dissipate.
You must complete a short or long rest before using this ability again. At 10th level, you may use this ability twice before resting and its damage increases to 2d8. At 15th level, you may use this ability three times before resting and the damage increases to 3d8.
Spectral Weapon
Beginning at 10th level, you gain the Grim Knight ability Spectral Weapon.
Spectral Weapon; As a bonus action on your turn, you call forth a spectral version of your bonded weapon to appear in an unoccupied space within 30 feet of you. You may then use this weapon to make a melee attack at a target within the weapon's range with all modifiers that apply to your normal weapon strikes. However, the damage done by this weapon is considered necrotic. If you make your first attack with this weapon, all subsequent attacks for that turn must be done with the spectral weapon as well. You may use your extra attacks feature with this weapon. Using your bonus action on subsequent turns you can maintain this summoning, allowing you to then take another attack action with it. The weapon is unable to move and you must maintain concentration on the spell, making a concentration check if you are attacked.
At 15th level, you may use your action to move the weapon up to 20 feet. You must complete a short or long rest before using this ability again.
Presence of the Master
At 15th level, any undead creature that attacks you must make a Wisdom saving throw against your spell save DC. On a failed save, the creature must choose a different target, or the attack automatically misses. On a successful save, the creature is immune to this effect for 24 hours. The creature is aware of this effect before it makes its attack against you.
Grim Reaper
Starting at 18th level, you can, as an action, summon a dark field of spectral chains in a 30 feet circle around you. The ground in this area becomes difficult terrain for the duration. When a creature enters the affected area for the first time on a turn or starts its turn there, it must succeed on a Dexterity saving throw or take 4d8 bludgeoning damage and be restrained. This damage is considered magical for the purposes of overcoming resistances or immunities. A creature that starts its turn in the area and is already restrained takes 4d8 bludgeoning damage. A creature may use its action to make a Strength check against your spell save DC, freeing itself on a success.
Any enemy killed in this field by you or an ally, triggers your Grim Harvest ability. Additionally, while this effect is active, you can use your action to automatically strike every restrained enemy within the affected area for 4d8 bludgeoning damage. (This damage is still considered magical as stated before). The chains remain in place for 1 minute or until you dismiss them.
You must complete a long rest before using this ability again.