Warlock Patron: The Beast

The Beast & The Unknown
he souls of the dead go to whichever plane they are intended for. From the Seven Heavens of Mount Celestia to the Nine Hells of Baator, from the Grey Waste of Hades to the Heroic Domains of Ysgard, from the Ever-Changing Chaos of Limbo to the Infinite Layers of the Abyss - each soul has its place.
But not all souls arrive. There is a place in between, where all souls spend some time. A thick dark forest, featuring boggy swamps and shallow rivers, this place is the Unknown.
Most souls quickly, intuitively find their way out and into the afterlife, to Pottsfield or beyond. Many spend so little time in
the Unknown that it takes but a brief instant, imprinting less than a fragment of a memory upon their souls. A rare few of great hope and courage even find their way home, not quite done with life.
For others, this in between place will span eternity. Give into despair or doubt, and all is lost. For the Beast will claim your soul, and you shall become just another of the Edelwood trees destined to be crushed into black oil for the Beast's Dark Lantern. Never do these souls see the afterlife.

DM Note:
The Beast is some form of evil, probably Neutral Evil. If the campaign at any point takes place in the Unknown, the Beast's desires are clear and easy (chop up Edelwood trees, make souls despair, etc.) However, this probably isn't the case for most of your campaign. In the Material Plane, or any other plane, the Beast's overall goal is still the same. He has the Woodsman (his primary Warlock) carrying and feeding the Dark Lantern, and needs souls for Edelwood trees.
Consider what actions he wants the PC to take in order to further his goal.
Perhaps he wants the Warlock to find people already in despair, and kill them. Perhaps wants the gods of the afterlife (Hades, Hel, etc.) toppled so that more souls are left to the Unknown. Whatever his immediate goals, they are unlikely to be good.

ELDRITCH INVOCATIONS
The following Eldritch Invocations are presented as options in addition to those in the Player's Handbook.

LANTERN OF THE UNKNOWN
Prerequisite: eldritch blast, Pact of the Lantern feature
When you cast eldritch blast, it is cast directly from your lantern without requiring somatic components. The damage type of the attack changes to psychic, and the damage die becomes a d12.

SOUL OF THE DARK LANTERN
Prerequisite: 17th Level, Pact of the Lantern feature
You have learned to do as the Beast has done, and place your
soul into your Dark Lantern. Your lantern no longer turns off when you are unconscious, and cannot be destroyed by means short of a disintegrate or wish spell. While your lantern is lit, you have advantage on death saving throws.
Additionally, if you die, your soul is transported to the Unknown and your lantern's light turns black and begins to pulse. Your lantern begins to call all evil creatures on its plane of existence toward it, until it is destroyed. In 1d10 days, if the lantern is still lit, your soul creates and inhabits anew body within 5 feet of the lantern and the light returns to normal.

WHISPERS OF THE EDELWOOD
Prerequisite: 9th Level, The Beast patron You can cast speak with plants at will, without expending a spell slot.

ported from GMBinder user u/Zacharr

Expanded Spell List

The Beast 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.

The Beast Expanded Spells

Language Of The Dark Forest

Beginning at 1st level, the Beast teaches you the secret language of its domain.
You know Druidic, the secret language of the druids stolen by the Beast. You can speak the language and use it to leave hidden messages. You and others who know this language automatically spot such a message. Others spot the message's presence with a successful DC 15 Wisdom (Perception) check but can't decipher it without using magic.

Come Wayward Souls

Starting at 6th level, your voice starts to rumble with the influence of the beast, lulling the ears and minds of listeners.
You gain prociency in the Deception and Persuasion skills. Your prociency bonus is doubled for any ability check you make using these skills.

Songs of the Dark Lantern

Additionally at 1st level, the Beast entices you to become a servant of the Unknown, desiring you to drag people into the depths of despair. You have a pool of d4s that you can use to spread this despair. The number of dice in the pool equals 1+ half your warlock level rounded up.
When a creature within 30 feet of you makes an attack roll, an ability check, or a saving throw, you can use your reaction to spend dice from the pool. The maximum number of dice you can spend at once equals half your charisma modier, rounded up (minimum of one die). Roll the dice you spent, and subtract the total from that attack roll, ability check, or saving throw.

Your pool regains all expended dice when you finish a long rest.

Shield of the Edelwood

Starting at 10th level, your association with the Beast turns aside other invasions upon your mind. You are immune to being charmed and have resistance to psychic damage.
Additionally, whenever a creature deals damage to you, you can use your reaction to teleport to a tree you can see within 90 feet, without provoking opportunity attacks.

Into the Unknown

At 14th level, your connection to the Unknown has become so potent that you can drag creatures into it at will.

As an action, choose up to 10 creatures you can see. If the target is unwilling, it can make a Wisdom saving throw. On a success, this feature has no effect on it. A willing target, or a creature who fails the save, is immediately transported to the Unknown. You are also transported into the Unknown.
In the Unknown, creatures have vulnerability to psychic damage and disadvantage on Wisdom saving throws and Wisdom (Insight) checks. Additionally, once per turn when you cast a spell, that spell deals extra psychic damage equal to your Charisma modifier (a minimum of 1 damage).
A small humanoid or child that dies in the Unknown becomes an Edelwood tree and remains there forever. Their soul is trapped and they cannot be brought back to life by any means short of a wish spell. All other creatures return to the plane from which they were dragged when they die, or after 1 minute.

Once you use this feature, you can't use it again until you finish a long rest.