Hi all! First post, so be gentle, please.

I'm riffing on some ideas I found two years ago on this forum from another user, Grod_The_Giant, to which I give him full and absolute credit for at least one ability here ("A Bug's Life," below), as well as a smattering of ideas from across the Internet. This is an idea I've been bouncing around myself for some time at my table, but I've never been quite sure how to tackle the balance of shifting into a swarm without either breaking the class' power curve (a la the Circle of the Moon) or making swarms useless compared to other options with Wild Shape (depriving them of health, resistances, and so on). Hopefully, this strikes some sort of a balance between the two. I'm interested to hear what you all think.

Swarm Shape

Beginning at 2nd level, you gain the ability to Wild Shape into a Swarm of any Small or smaller creature. This feature otherwise functions exactly as does a regular druidís wild shape, except that instead of turning into a Beast, you turn into a Beast with the Swarm subtype and property, along with the following bonuses for the duration:

- Resistance to bludgeoning, slashing, and piercing damage;
- Immunity to the Charmed, Frightened, Grappled, Paralyzed, Petrified, Prone, Restrained, and Stunned conditions;
- Hit dice equal to your Druid level plus your Proficiency modifier in the original creature's denomination (for calculating hit points);
- 2d6 damage at full health and 1d6 damage at half health of the creature's damage type and restrictions, or an additional d6 damage at full health if the creature's default damage is 2d6 or higher.

Swarms shaped into in this way are Medium in size. Swarm shape may be used in place of wild shape for prerequisites, and daily uses of swarm shape count as daily uses of wild shape. Feats and features that modify wild shape may modify swarm shape.

A Bug's Life

Beginning at 2nd level, you have advantage on Intelligence (Nature) checks to recall information about insects, rats, and other vermin, and you may attempt to influence their behavior with a Wisdom (Animal Handling) check. In addition, you learn the Infestation and Acid Splash cantrips, which do not count towards you total number of cantrips known. If you already have these cantrips selected, you may choose any other cantrip on the Druid spell list.

Improved Swarm Shape

Beginning at 6th level, and at every third level thereafter, you gain the ability to shape yourself into an additional swarm at the same time. All swarms must be adjacent to each other and either include or be adjacent to the space you occupied before assuming the shape. You command all swarms simultaneously, but they are otherwise treated as separate creatures under your control for all practical purposes. Any swarm you share a space with reports information back to you, equivalent to experiencing it yourself. When you shape into multiple swarms, multiply your Druid level by the amount of swarms you are shaped into while calculating hit dice and distribute the result evenly among them. You die only if all swarms you are shaped into die.

Venom Veins

Beginning at 6th level, you become immune to all poison and disease.

Safety in Numbers

Your swarm can now shield you from mortal damage. Beginning at 10th level, if you are reduced to less than one hit point in a single turn while wild-shaped as a Swarm, you take half the total expected damage and survive as a single member of that Swarm, with the appropriate statistics thereof. This ability does not apply if the total damage received exceeds twice your hit-point maximum.

One of Us

Beginning at 14th level, you may add any two creature types to the list of creature types you can turn into with swarm shape, other than Humanoid. The chosen creature types must still meet all the criteria for wild shape aside from type and subtype. In addition to the normal effects of wild shape, you gain all of the selected creature's extraordinary, supernatural, and spell-like abilities for the duration.

So yeah, that's everything. As a note, I opted to add proficiency bonus to the hitpoint calculation to help it scale with level; it makes sense to me that a lower-level or less experienced druid might conjure up less creatures in a swarm than an experienced, higher-level one.

I'm also concerned about Venom Veins. It seems like a bit of a throwaway at 10th level.

Again, I'm open to all feedback. Please let me know!

(Grod, if you're reading this: I absolutely loved your original thread about this topic, and I hope you approve!)