I was curious what making a new Warlock patron would look like.  It ended up looking like this.

I’m also sort of feeling like there should be some system for explicit patron boons.  They ask you to do something and offer short term rewards.  Easiest way to do it is as its own form of inspiration, rather like the sorcerer’s Tides of Chaos.  If you have the patron’s boon, it can be turned in for an advantage, but then it’s gone until you earn it again.

Anyway, I’m not 100% sure about some of the balance of this stuff, but it feels like the right ballpark.

The Grey Tyrant

At the edge of the universe, where all things end, a grey king sits upon a grey throne in grey castle under a grey sky. He surveys the end of all things. Not mere death, but ending, and the final moment of stillness before all returns to the void. Fools think that only chaos can destroy, but the void is the perfect orderly end of all thing, where stasis and nothingness are one and the same, and it is his domain.

He does not move from this throne, for all things come to him in time, but he offers power for those who speed things along.

Grey Tyrant Expanded Spell List

Spell Level	Spells
1st	Fog Cloud, Ray of Sickness
2nd	Gentle Repose, Ray of Enfeeblement
3rd	Dispel Magic, Protection from Energy
4th	Banishment, Stoneskin
5th	Cloudkill, Wall of Force

Eyes That See All Endings

Starting at first level, the Grey Tyrant gives you the ability to see the world as he does, as a place of vulnerabilities and endings. If you take an action to look up on a target through the Grey Tyrant’s eyes, it makes a Wisdom saving throw against your warlock spell save DC. If it fails, you learn the target’s vulnerabilities.

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

Stroke of Ending

Starting at 6th level, your magics can turn to bring about endings. Before you roll damage for a spell that inflicts typed damage (fire, cold etc) against a target, you may use this ability to change it to any other type, so long as you know a spell that can do damage of that type.

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

Stasis and the Void

Starting at 10th level, you may become as unchanging as void in order to shrug off attacks. As a reaction, you may become petrified. You keep this status until your next turn.

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

Even Energy Ends

Starting at 14th level, the barrier between energy and matter fades for you, and you may shape magic with you very hands.

When you successfully save against a damaging spell, you take no damage. Instead, you create a weapon (or surround a weapon you are holding with a nimbus) of the spell’s energy. If created, it takes the form of any weapon you are proficient with. The next target struck with the weapon will take additional damage of an amount and type as if they’ve been hit by the spell itself, though no other effects convey.

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

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Additional Warlock Abilities

Came up with these to supplement the Grey Tyrant, so there’s overlap there, but it’s not required.  The Pact of Iron was really because warlocks in demonic black armor just seems *right* to me.

Pact Boon: Pact of Iron

If you are not wearing armor, you can use your action to summon pact armor, a weightless suit of armor whose appearance is determined by its summoner, ranging from mundane black iron to fantastical configurations of smoke and glass. This armor disappears if you remove it, if you dismiss it (no action required), or if you die.

The pact armor grants an AC of 15 + Dex Modifier (max 2), weighs 0 lbs, and offers no disadvantage to stealth. The Warlock is considered proficient in it.

You can absorb the properties of one suit of magical armor into your pact armor by performing a special ritual while wearing it over the course of an hour, at which point the armor dissolves into nothingness (and cannot be returned) and your pact armor gains the magical effects of the absorbed armor. If you perform this ritual again, the original bonuses are lost.

Eldritch Invocations

Ender of All

Prerequisite: 12th Level

You may cast disintegrate as a level 6 arcanum

Power in Endings

You may have advantage or disadvantage on death saves, as you choose. Whenever you fail a death save, regain the use of one spell slot.

Unyielding Armor of the Void

Prerequisite: 9th Level, Pact of Iron

AC of your pact armor increases to 18