One of my D&D groups will be starting a level 5–20 campaign soon, and I have a character concept I'd like to use for it. Briefly, the character is a warlock whose patron is a mysterious coven from a deep ocean realm. The patron is similar to the Fathomless patron from Tasha's Cauldron of Everything, but it is specifically interested in observing and gathering information about the material plane for some possibly sinister purpose that is unknown to the character; accordingly, it provides powers that are more focused on divination. In borrows somewhat from the Sorcerer of Mirrors sub-class I wrote up some time ago but is too different to call a revision. Making a new subclass in this case feels necessary to me because there are no warlock subclasses who focus on divination.
TL;DR—this class is based on, but deviates substantially from, the Fathomless class and emphasizes divination. I'm interested in knowing if it is unbalanced or otherwise problematic before I bring it to my DM.
The Coven, Still
You have made an arrangement with a mysterious entity that calls itself "the Coven, Still". The Coven appears to you in still pools and speaks to you whenever you are underwater, using myriad voices that always drift from wherever the water is deepest. Always, it asks you questions, some mundane, some insightful. What is clear is that the Coven, Still, is alien and powerful yet eager to know as much as it can about your experience. It seems to believe that you are fated to witness an event of great importance, and it is content to lend you its power in order to witness the event through your eyes.
Expanded Spell List
Level 1 Coven Feature.
The Coven, Still, 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 Coven's expanded spell list changes one spell per level from the Fathomless expanded spell list into a divination spell or a more on-theme spell. I do not think that these spells are going to be game breaking in any way, and in fact probably slightly lower the class's combat effectiveness overall.
Level 1 Coven Feature.
At 1st level, you can magically summon a spectral watery being that appears as an amorphous rippling disturbance in the air. As a bonus action, you create a medium-sized specter at a point you can see within 60 feet of you. The specter lasts for 1 minute or until you use this feature to create another specter.
When you create the specter, you can make a melee spell attack against one creature within 10 feet of it. On a hit, the target takes 1d8 cold damage, and its speed is reduced by 10 feet until the start of your next turn. When you reach 10th level in this class, the damage increases to 2d8.
As a bonus action on your turn, you can move the specter up to 30 feet and repeat the attack.
You can summon the specter a number of times equal to your proficiency bonus, and you regain all expended uses when you finish a long rest.
When the specter makes an attack against a creature, it takes on the appearance of a spectral reflection of the creature that ripples as if were reflected off of the surface of a pond.
The Watery Specter feature is identical to the Tentacles of the Deep feature from the Fathomless with two exceptions: (1) the fluff is changed from being about a tentacle to being a watery reflection, and (2) the size is changed from 10 feet long to medium in size. I think these are fairly trivial.
Insight of the Still Mind
Level 1 Coven Feature.
When you cast a divination spell that requires concentration, you may optionally change its duration to a number of hours equal to your proficiency bonus.
This feature replaces the Gift of the Sea feature from the Fathomless. The Fathomless feature is probably more practical (underwater breathing and a swimming speed), but this feature is nice for a warlock who only has a few spell slots and often won't want to use them on short-lived divination magic. My concern is that the feature might be abusable in some way I haven't seen. Going through the divination spells, I only see a few spells where this feature is a major power buff, however: Detect Thoughts in particular gains a lot at a low level, and Clairvoyance and Scrying both gain a fair amount of utility. Being able to cast spells like Detect Magic and Locate Object for hours instead of minutes with a low-level spell slot seems nice for a warlock but not game breaking.
Visions of Still Pools
Level 6 Coven Feature.
If you are within 5 feet of a still pool of water such as a lake, pond, puddle, or bowl of water that you can see, you may ignore all components of any divination spell that you cast except material components that are consumed by the spell and you do not become blinded to your own senses should the spell typically require it. When you cast a spell in this way, you may optionally cause images to be visible in the pool to any creature of your choice within 30 feet of it. Any sensory information that you gain from the divination spell is also communicated directly via these images to any creature that can see them. If the spell provides audible information, then sounds instead of images emanate from the pool and must be heard.
Additionally, you may cast the Clairvoyance spell in such a pool without spending a spell slot. Once you have cast Clairvoyance using this feature, you may not cast it using this feature again until you have completed a short or long rest.
This feature takes the place of the Oceanic Soul feature from the Fathomless class, which provides cold resistance and universal speech while submerged underwater. The first part of this feature is really just a party-friendly update to a few divination spells (clairvoyance, arcane eye, and scrying) in that it lets the whole party enjoy the spell instead of just the caster. Since it only provides sensory information and not bonuses, it will have a small effect on the game mechanics overall. The second part grants a nice but non-combat spell to the warlock. Being able to cast Clairvoyance once per short rest gives the party a lot of access to general remote viewing magic at a moderately low level, but this shouldn't be unbalanced unless the particular campaign's design relies on parties having relatively little access to this kind of magic. Notably this doesn't grant the warlock the Clairvoyance spell itself, so it doesn't grant the warlock the ability to cast it more than once per short rest.
Level 6 Coven Feature.
At 6th level, your Watery Specter can defend you and others, interposing itself between them and harm. When you or a creature you can see takes damage while within 10 feet of the specter, you can use your reaction to choose one of those creatures and reduce the damage to that creature by 1d8. When you reach 10th level in this class, the damage reduced by the specter increases to 2d8.
This feature is identical to the Guardian Coil feature from the Fathomless class except for the name and fluff.
Level 10 Coven Feature.
Starting at 10th level, you learn the spell Scrying. It counts as a warlock spell for you, but it doesn't count against the number of spells you know. You can also cast it once without using a spell slot, and you regain the ability to do so when you finish a long rest.
Whenever you use this feature to cast Scrying, you successfully target a creature with it, and you concentrate for the spell's full duration, you gain an uncanny insight into the creature. The DM tells you if the creature is your equal, superior, or inferior in regard to one of the following characteristics of your choice:
- Charisma score
- Wisdom score
- Intelligence score
Additionally, the DM tells you one of the following:
- 1d6 randomly-chosen spells that the creature is currently capable of casting, if any
- One randomly chosen spell currently affecting the creature, if any
- One randomly chosen resistance or immunity that the creature has, if any
This feature replaces the Fathomless feature "Grasping Tentacles," which provides the Evard's Black Tentacles spell and some temporary hit points when casting that spell. Similarly, this feature grants the Scrying spell and some extra information when casting that spell. The extra information is similar to the "Know Your Enemy" feature from the Battle Master Fighter but provides complementary information. Overall, my intuition is that this reduces the class's in-combat potential compared to the Fathomless class, but provides a party that favors planning with a strategic way to weaponize divination. Note that Scrying is already a warlock spell.
Through the Scrying Pool
14th Level Coven Feature.
When you reach 14th level, you can magically open temporary conduits to watery destinations. Whenever you are concentrating on the Scrying spell, as an action, you can teleport yourself to the location you are remotely viewing as long as you can see a pool of still water at the remote destination (the surface of the pool must have an area that is at least 5 square feet). If you used the Visions of Still Pools feature to cast the spell, you may take up to 5 willing creatures who can also see the destination with you. Each of you appears in an unoccupied space within 30 feet of the others.
Once you use this feature, you can't use it again until you finish a long rest.
This feature replaces, but is similar to, the Fathomless feature Fathomless Plunge, which teleports you and up to 5 friends to a watery location within a mile. Whereas Fathomless Plunge is useful as a quick get-away, this feature is useful as a strategic approach or long jump for the whole party. This allows a level 14 warlock to teleport the entire party all the way across the plane once per day as long as they know someone or somewhere to scry on that also has a pool of water; for long-distance travel this is a very nice feature. However, it's comparable in power to the Transport via Plants spell, which a druid gains at level 11, and the Plane Shift spell, which a warlock can gain at level 13. This seems powerful but probably not game-breaking at level 14 to me; however, if I've overlooked something, a reasonable modification might be to limit it to the Arcane Eye and Clairvoyance spells only.
This subclass is a warlock that focuses on making divination magic more useful to the whole party and favors a party that wants to plan encounters carefully. It starts with the Fathomless Patron, which feels to me like a fairly powerful patron, and swaps several of the utility features for divination features. For the most part, these new features do not grant abilities that cannot be gained at similar levels by other means, so they do not seem inherently overpowered to me. Overall this subclass is probably less powerful in combat than the Fathomless, but since the Fathomless class is powerful in combat to begin with, that is probably fine. Instead, the subclass gains abilities that are useful to the party strategically, and are probably especially good for teams that favor planning.