Tasha's, Class by Class - Warlock

 Ah, Warlocks. I love Warlocks, even if their spellcasting is somewhat limited compared to, say, a Wizard's. But the inherent story, and the massive degree of customization available to them, is really pretty amazing. Let's look at what they get in Tasha's Cauldron of Everything:

Class Features:

New Spells: Like all casters, there are some new spells for Warlocks to take. In addition to the new spells that come in the book (along with reprints from SCAG and Rime of the Frostmaiden) there are also some PHB spells that Warlocks can now use, namely: Mislead, Planar Binding, Teleportation Circle, Gate, and Weird, which all feel pretty flavorfully Warlock-y.

New Pact Boon:

There's now a fourth Pact Boon option for level 3: the Talisman. While wearing it (and you can give this to another person if you want to,) when a creature fails an ability check, they can add a d4 to it and potentially turn that failure into a success, which they can do a number of times equal to your proficiency bonus per long rest.

Eldritch Versatility:

Any time you get the Ability Score Improvement feature, you can also swap out a Warlock cantrip, choose a different Pact Boon, or change one of your Mystic Arcanum spells for one of the same level. Also, if any of these choices make you ineligible for any Invocations you already have, you can swap those out for ones you are eligible for. This is a pretty nice Quality of Life change to enshrine in the rules.

New Eldritch Invocations:

You knew we'd get some of these!

Bond of the Talisman (12th level, Talisman Pact)

You and the person wearing your talisman can now teleport to one another as an action as long as you're on the same plane of existence, a number of times equal to your proficiency bonus per long rest. The buddy system!

Eldritch Mind:

You have advantage on Concentration saves.

Far Scribe (5th level, Tome Pact):

You can write a number of names (with the person's permission) equal to your proficiency bonus into your Book of Shadows (and you can also erase a name as an action if you need to free up space) and then you can cast Sending to any of those people as long as you can write the message to them, and their response comes back as text, which disappears after a minute. And there's no limit on how many times you can do it!

Gift of the Protectors (9th level, Tome Pact):

You can write a number of names equal to your proficiency bonus (again, with the person's permission) into your Book of Shadows. When a named creature drops to 0 hit points and isn't killed outright, they drop to 1 instead, and then the feature can't go off until you finish a long rest.

Investment of the Chain Master (Chain Pact):

Your familiar becomes a lot better in myriad ways - gaining a flying or swimming speed of 40 feet, allowing you to command it to attack with a bonus action, getting magical attacks, using your spell save DC for any saving throws it forces the target to make, and allowing you to use your reaction to give it resistance to damage it takes. Basically, this makes the familiar a bigger part of your combat options.

Protection of the Talisman (7th level, Talisman Pact):

The wearer can add a d4 to failed saving throws, potentially making them successes. Usable a number of times equal to your proficiency bonus.

Rebuke of the Talisman (Talisman Pact):

When the wearer is hit by an attacker you can see within 30 feet, you can use your reaction to have them take psychic damage equal to your proficiency bonus and push them 10 feet away from the wearer.

Undying Servitude (5th level)

You can cast Animate Dead once per long rest without using a spell slot. Hooray for Warlock Necromancy!

New Subclasses:

Yes, we've also got those!

The Fathomless:

The concept here is that your patron is an ancient, deep-sea creature. While the most obvious would be something like a Kraken, or Uko'toa from Wildemount, this could technically be any entity from deep waters, even the elemental plane of water. Naturally, there's a bit of a Lovecraftian feel to this as well (though it occurred to me a few days ago that a Kraken is, more or less, a Lovecraftian monster, as a being of profoundly ancient origin, mostly hidden from the surface world, powerful enough to be an apocalyptic threat, and tends to have weird cults and stuff dedicated to it.)

The subclass has a strong tentacle theme - allowing you to manifest a tentacle that attacks foes, and defends you. You also get a swim speed, cold resistance, and the ability to breathe water, as well as the ability to teleport your party up to a mile, as long as you wind up within a body of water (which could be anything from an ocean to a small pond.)

This would naturally be a great fit for a nautical campaign, and can be flavored in very different ways.

The Genie:

This is one that always felt obvious, and I'm glad they've made it happen!

First off, this is kind of four subclasses in one - you choose between either a Dao (Earth), Djinni (Air), Efreeti (Fire), or Marid (Water) and get different expanded spell lists based on your choice, as well as a spell for each of the first five spell levels for all Genie Warlocks. Additionally, beyond the 1st-5th level spells, every Genie Warlock can take Wish as their 9th level Mystic Arcanum. Which I have to imagine any Warlock in their right mind would do.

But, beyond Wish (which, man, that's probably enough to sell me on it already) there are also, of course, some class features. The big theme is that you get a Genie's Vessel - a bottle, lamp, or other classic Genie-holder. You can use this as a spell focus (and get it back if you lose it). You can enter the vessel once a day and use it as both a nice lounge to chill in as well as a storage space. At level 10, you can take friends there, and if you spend 10 minutes inside, you get the benefits of a short rest.

You also get some extra damage and resistances based on your patron's genie type, as well as a "limited wish" feature at level 14 that lets you get any 6th level spell or lower if it can be cast with one action - without needing to provide costly spell components - a nice clutch revivify, greater restoration, etc.

    So I've technically already played two Warlocks, but damn if this isn't making me want to play another! The Genie feels like a way to play a much less sinister-seeming Warlock, which could be a ton of fun.