Tasha's Cauldron of Everything introduced, among other things, a huge selection of new subclasses. It features 18 spellcaster subclasses, some reprinted from various other books and some revised from Unear♏thed Arcana. Here's the definitive ranking.
18. Battle Smith
This artificer subclass was not bad🍌 when it was released in Eberron: Rising from the Last War. It isn’t bad now either, but the idea of a heavily-armored frontline artificer is less novel and the Battle Smith pales in comparison to the much cooler Armorer. The one advantage that this subclass has over the Armorer is the robot pal that comes with it. If you want a mechanical friend, go for it. Otherwise, the A♓rmorer is just generally better.
17. Peace Domain
Conceptually, this cleric domain is great. Mechanically, it’s lacking. The idea of pacifist▨ (or pacifist-adjacent) subclasses is not a new one, since Xanathar's Guide to Everything features the Oath of Redemption paladin. The Peace Domain doesn’t mechanically support the concept as well as the paladin, though. Most of its abilities are based on establishing a bond between two allies, which is interesting in theory, but in practice mostly consists of dropping it on party members at the beginning of a battle and forgetting about it.
16. Circle of Wildfire
This druid subclass has a fairly simple theme—fire druid. Unfortunately, an entirely fire-based subclass runs into the problem of fire resistance; it is the most common type of resistance, so you’ll want to take the Elemental 🐠Adept feat for your spells. Most of this subclass’s abilities are based around a new use for Wild Shape that summons a wildfire spirit that is bonded to you. The wildfire spirit isn’t a bad summon, but it thematically changes Wild Shape from a transformation ability to a minion-mancer one. The wildfire spirit doesn’t gain any benefit from Elemental Adept either, so it run𒁃s into the resistance problem too.
15. Clockwork Soul
Both sorcerer subclasses are pretty powerful due to their spell lists alone. Normally, sorcerers have a limited spell list and limited number of known spells. The Clockwork Soul offers 10 more known spells for free as you level up. Even better, these spells can be retrained into any abjuration or transmutation spell from the sorcerer, warloc♑k, or wizard spell lists. This is a huge bonus, especially for sಞorcerers.
Other than that, this subclass suffers from not being very interesting. The Wild Magic sorcerer is interesting because it embodies chaos, which it defines as “weird stuff happening.” The Clockwork Soul seems to define order as “weird stuff not happening.” It does have a very interesting ability at 18th level, but it’s too situational🉐 to save the su🐼bclass.
14. The Fathomless
This warlock patron has a lot of abilities that depend on you being in or near water, so if you’re in a nautical campaign, feel free to bump this class up to the to🍸p three. Otherwise, it’s just too reliant on being near the water. The ability to create a tentacle that can deal damage and decrease enemy attacks is a solid central mechanic, and resistance to cold damage is good. Pick it up when you play Ghosts of Saltmarsh or another nautical adventure; otherwise, you’ll just be wishing you could use your abilities.
13. Alchemist
This artificer subclass is solid, if not flashy, and delivers ex🅘actly what it promises. If you want to do alchemy, the Alchemist is a good choice. You get a mystery potion, bonuses to healing and some flavorful damage types, and nice resistances. At high levels, you can cast some healing and restoration spells for free, which is less interesting than original abilities, but function well in the subclass and round it out as a decent support.
12. Artillerist
This artificer subclass is very flashy, but that is to be expected from a subclass whose sole focus is basically “magic guns.” Despite being focused around the ability to make cannons, the subclass has some good defensive capabilities for an entire party. The cannons get better as you level up, too, with more damage and more guns. The concept is a fun one as well. Who doesn🐲’t enjoy the novelty of using a bunch of magic guns to blast enemies?
11. Twilight Domain
A good number of this cleric subclass’s abilities relate to, or at least interact with, the domain’s Channel Divinity ability. This means that before 18th level, you’re going to be able to use it at most a couple times per short rest. On the other hand, the Twilight Sanctuary Channel Divinity is very good, giving temporary hit points or ending charmed/frightened to every ally every round. With a radius of 30 feet, it will take u𒆙p most of the space of many battlefields, and with a durꦉation of one minute it will last longer than many fights. The ability to fly in dim light (which your Channel Divinity creates) or darkness is amazing, and super-darkvision is good as well. Overall, it does as well as a subclass based around dim light can do.
10. Aberrant Mind
This sorcerer subclass was envisioned as a psionic subclass, but ended up being more of a sorcerer version of the Great Old One warlock. However, as a cosmic-horror-esque sorcerer, it’s pretty good. It has t🍃he same type of subclass-specific spellcasting as the Clockwork Soul sorcerer, which is, again, amazingly beneficial to a sorcerer’s limited spell list. It also lets you cast these extra spells using sorcery points at a good rate. The l𝐆ater abilities give a wide variety of useful and flavorful mind-and-tentacle-based powers that are good at every level.
9. Bladesinging
Bladesingers are wizards that can swing a sword, but in a more wizard-y way than Eldritch Knights or Arcane𝔉 Tricksters. They get abilities that let them survive in battle and use weapons, while still retaining the extensive wizard spell list. However, you still have the regular wizard health pool, so when you do take hits you go down fast. Still, it’s a good subclass for a wi⛄zard-fighter that wants to be more wizard than fighter.
