Warriors corrupted by the lower planes, touched by the primordial chaos of the Abyss, the devilish charms of Asmodeus' Nine Hells, or even the soul-draining greed of darker regions, Fiendish Instruments are conduits of destruction for their demonic or devilish overlords. These Fighters are often power-hungry or vengeance-seeking mortals who have forfeited their souls in exchange for demonic abilities. Just as often, they are unwittingly committing acts of evil under the influence of a succubus. Some do so to accomplish a mundane goal, believing these profane powers help them conquer kingdoms or hoard wealth; others do it for a more nefarious reason: expecting to fight in the Blood War as generals, reincarnated as a balor after their deaths. The most ignorant and foolish of them think they can master this dark path, unaware that even the most hardened or pure-hearted warrior eventually succumbs to evil, madness, or sometimes...both.

Their spells complement and extend their combat skills, providing additional protection to shore up their armor and allowing them to engage many foes simultaneously with explosive magic.

Level 3: Spellcasting

You have learned to cast spells.

Cantrips. You know two cantrips of your choice from the Sorcerer spell list. Whenever you gain a Fighter level, you can replace one of these cantrips with another cantrip of your choice from the Sorcerer spell list.

When you reach Fighter level 10, you learn another Sorcerer cantrip of your choice.

Spell Slots. The Fiendish Instrument Spellcasting table shows how many spell slots you have to cast your level 1+ spells. You regain all expended slots when you finish a Long Rest.

Fiendish Instrument Spellcasting

		—Spell Slots per Spell Level—
Fighter Level	Spells Prepared	1	2	3	4
3	3	2	—	—	—
4	4	3	—	—	—
5	4	3	—	—	—
6	4	3	—	—	—
7	5	4	2	—	—
8	6	4	2	—	—
9	6	4	2	—	—
10	7	4	3	—	—
11	8	4	3	—	—
12	8	4	3	—	—
13	9	4	3	2	—
14	10	4	3	2	—
15	10	4	3	2	—
16	11	4	3	3	—
17	11	4	3	3	—
18	11	4	3	3	—
19	12	4	3	3	1
20	13	4	3	3	1

Prepared Spells of Level 1+. You prepare the list of level 1+ spells that are available for you to cast with this feature. To start, choose three level 1 spells from the Sorcerer spell list.

The number of spells on your list increases as you gain Fighter levels, as shown in the Prepared Spells column of the Fiendish Instrument Spellcasting table. Whenever that number increases, choose additional spells from the Sorcerer spell list until the number of spells on your list matches the number on the table. The chosen spells must be of a level for which you have spell slots. For example, if you’re a level 7 Fighter, your list of prepared spells can include five Sorcerer spells of levels 1 and 2 in any combination.

Changing Your Prepared Spells. Whenever you gain a Fighter level, you can replace one spell on your list with another Sorcerer spell for which you have spell slots.

Spellcasting Ability. Charisma is your spellcasting ability for your Sorcerer spells.

Spellcasting Focus. You can use an Arcane Focus, or a weapon you have bonded with via your Devil's Bond feature, as a Spellcasting Focus for your Sorcerer spells.

Level 3: Devil's Bond

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. The bond fails if another Fighter is bonded to the weapon or if the weapon is a magic item to which someone else is attuned.

Once you have bonded a weapon to yourself, you can’t be disarmed of that weapon unless you have the Incapacitated condition. If it is on the same plane of existence, you can summon that weapon as a Bonus Action, causing it to teleport instantly to your hand.

You can have up to two bonded weapons, but you can summon only one at a time with a Bonus Action. If you attempt to bond with a third weapon, you must break the bond with one of the other two.

Level 7: Abyssal Step

Your patron grants you the ability to move between the boundaries of the planes, but the experience is incredibly taxing to your mortal form. You can cast Misty Step without expending a spell slot a number of times equal to your Constitution modifier, and you regain all expended uses when you finish a Long Rest.

In addition, whenever you cast that spell, you can choose one of the following additional effects.

Taunting Step. Creatures within 5 feet of the space you left must succeed on a Wisdom saving throw against your spell save DC or have Disadvantage on attack rolls against creatures other than you until the start of your next turn.

Blazing Step. Creatures within 5 feet of the space you left or the space you appear in (your choice) must succeed on a Dexterity saving throw against your spell save DC or take [roll]2d4[/roll] fire damage.

Level 10: Infernal Strike

The most skilled warriors of the Lower Planes have instructed you how to deploy your arcane and martial skills simultaneously. When you take the Attack action on your turn, you can replace one of the attacks with a casting of one of your Sorcerer cantrips that has a casting time of an action.

Level 15: Mark of the Instrument

The Lower Planes have left an indelible mark on you, for better or worse.

You can see normally in Dim Light and Darkness—both magical and nonmagical—within 120 feet of yourself. You also gain resistance to fire, psychic, and poison damage.

Level 18: Improved Infernal Strike

When you take the Attack action on your turn, you can replace two of the attacks with a casting of one of your level 1 or level 2 Sorcerer spells that has a casting time of an action.