Dullahan (The Headless Horseman)

Your patron is a mysterious being called many names; the Wild Huntsman by some, the Headless Horseman by others, and to scholars and its servants, it is known as the Dullahan. More active on the Material Plane than many others of its kind, the Dullahan is a reaper and debt collector both, a figure whose arrival is a harbinger of dark times to come. It collects the souls of those who are fated to die, and reaps those who have escaped the clutches of death; the only way to ward against this creature, so it is said, is with purest gold. Against the cunning few who exploit this flaw, those it cannot reach, or those considered unworthy of its time, the Dullahan sends its mortal servants, who wield a fraction of its power over life and death - and for whom gold is no obstacle.

(For Eldritch Invocations for this subclass, search for "Gan Ceann Invocation")

Credit to u/VampireBagel_   glad I found this, thought I'd share with DNDBeyond.

The Horseman's Spell List

Dullahan lets you choose from an expanded list of spells when you learn a warlock spell. The following spells are added to the warlock spell list for you.

Dullahan Expanded Spells

Spell Level	Spells
1st	command, sleep, faerie fire
2nd	find steed, pass without trace
3rd	blink, speak with dead
4th	arcane eye, phantasmal killer
5th	cone of cold, dispel evil and good

Reaper's Mark

Starting at 1st level, you gain the ability to place a baleful curse on someone. As a bonus action, choose one creature you can see within 30 feet of you. The target is cursed for 1 minute. The curse ends early if the target dies, you die, or you are incapacitated. Until the curse ends, you gain the following benefits:

• Once on each of your turns when you deal damage to the cursed target, it must make a Wisdom saving throw against your spell save DC or be frightened of you until the end of its turn.
• While the target is cursed you are always aware of its location and it cant be hidden from you.
• If the cursed target dies, you regain hit points equal to your warlock level + your Charisma modifier (minimum of 1 hit point).
• You can't use this feature again until you finish a short or long rest.

Grains Of Sand

Starting at 6th level, you can delay lethal damage for a time, or negate it by offering your attacker's life in place of yours.
When a creature deals damage to you, you can use your reaction to take none. At the end of your next turn, you take half the damage you would have taken. If the creature that dealt the triggering damage is reduced to 0 hit points before the end of your next turn, you instead take no damage.
Once you've used this feature, you can't use it again until you finish a short or long rest.

Fear Itself

Beginning at 10th level, you know no fear. You are immune to being frightened, and when another creature attempts to [Tooltip Not Found] you, you can use your reaction to attempt to turn the fear back on that creature. The creature must succeed on a Wisdom saving throw against your warlock spell save DC or be frightened of you for 1 minute. The frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Tolling Of The Bell

Starting at 14th level, when a creature within 30 feet of you is reduced to 0 hit points, you can use your reaction to cause a wave of necrotic energy to be released from its body. Any creatures of your choice within 30 feet of the creature, must succeed on a WIS saving throw, or take 3d8 necrotic damage and be frightened of you until the end of your next turn.