Forgotten Invocations
In the Unearthed Arcana: Wizard and Warlock article, the warlock class received additional Eldritch Invocation options specific to individual Otherworldly Patrons. The Celestial and The Undying were the subclasses to be left behind: even The Hexblade, which was released alongside The Celestial in Xanathar's Guide to Everything, was treated to this addition. This document provides a handful of exclusive invocations for Celestial and Undying warlocks to harness.
The Celestial
Hand of Five Fates
Prerequisites: Celestial patron
Once per long rest, you can cast bless using a warlock spell slot.
Angelic Beacon
Prerequisites: 5th level, Celestial patron
Once per long rest, you can cast beacon of hope without expending a spell slot.
Brand of Retribution
Prerequisites: Celestial patron, hex spell or a warlock feature that curses
Your hex spell, in addition to any warlock feature you have that applies a curse such as Sign of Ill Omen, deals radiant damage instead of necrotic. In addition, when you see the hexed or cursed creature make an attack and is within 60 feet of you, you can use your reaction to end the hex or curse and subtract your Charisma modifier from the attack roll.
Blade of Evil's Bane
Prerequisites: 9th level, Celestial patron, Pact of the Blade
Once per long rest, you can cast holy weapon on your pact weapon using a warlock spell slot.
Blessed Guardian
Prerequisites: 9th level, Celestial Patron, Pact of the Chain
Your familiar permanently gains the benefits of the sanctuary spell, and can use an action to pass the spell's effects onto another creature for 1 minute. Upon doing so, your familiar loses the benefits of sanctuary until you finish a long rest.
Crusader's Arcanum
Prerequisites: Celestial patron, Pact of the Tome
You can cast any cleric spell from a spell scroll as though it were on the warlock spell list. You can ignore the material components of warlock spells you cast with a listed gold cost no higher than five times your warlock level.
In addition, for each of your Mystic Arcanum features starting at 13th level, you may choose a spell from the cleric or warlock list.
Why So Spooky?
The warlock class as a whole could be called "dark" in many of its thematics, especially when it bears such Eldritch Invocations as Armor of Shadows, Fiendish Vigor, and Whispers of the Grave. The Celestial is the exception to this trend, being a largely good-oriented class.
Feel free to ask your DM about reflavoring your invocations to sound less foreboding, such as replacing the prior examples with Armor of Light, Angelic Vigor, and Call of the Departed, respectively. Whether or not these changes will actually bring mechanical alterations is at the discretion of your DM.
The Undying
Surge of Unlife
Prerequisite: Undying patron
You can cast spare the dying as a bonus action. When you target a creature with spare the dying, it regains 1 hit point after 1d4 rounds instead of 1d4 hours.
Hollow Defiance
Prerequisite: 7th level, Undying patron
When you roll a death saving throw while you are already at two failures or two successes, you can roll with advantage.
In addition, whenever you return to consciousness after gaining at least 1 hit point while at 0 hit points, you can give yourself temporary hit points equal to your warlock level + your Charisma modifier. Once you use this effect, you cannot do so again until you finish a long rest.
Vigorous Suffision
Prerequisites: 12th level, Undying patron
As long as you are not concentrating on a spell, you emit an aura out to a radius of 10 feet identical to the aura of purity spell.
Wicked Hex
Prerequisite: Undying patron, hex spell or a warlock feature that curses
Whenever the target of your hex spell makes a saving throw of the ability you chose for that activation of hex, it must roll 1d4 and subtract the result from the saving throw.
In addition, if you would roll a number less than your Charisma modifier on the damage die for your hex spell or other curse that deals necrotic damage, you may replace the die with your Charisma modifier.
Lifesapper
Prerequisite: Undying patron, Pact of the Blade
When you score a critical hit with your pact weapon, the target takes additional necrotic damage equal to your warlock level, and you regain hit points equal to half the necrotic damage dealt in this way.
Master of the Returned
Prerequisite: Undying patron, Pact of the Tome
You can cast any necromancy spell from a spell scroll as though it were on the warlock spell list.
In addition, you roll all Intelligence checks made to learn the nature of cursed items with advantage. If the curse was laid by an undead, you learn more of the undead that originally laid the curse than someone who does not have this feature, even if they would have rolled the same number as you on the Intelligence check.
