Here’s a homebrew D&D 5E druid archetype I’ve been working on: The Circle of the Swarm. They are similar to Circle of the Moon druids, except they are able to Wild Shape into swarms of tiny beasts.
While swarms have strong immunities and resistances, they have relatively low hit points, armor class, saving throws, the inability to regain hit points or gain temporary hit points, and they deal half damage when they have half or fewer hit points. Also for balance and thematic reasons, they are unable to maintain concentration while in swarm form.
Since swarms cannot regain hit points, I thought it necessary to replace the Combat Wild Shape self-healing ability with something else, in this case two options that harken back to earlier editions: blighted swarms channel spell slots into additional necrotic damage, and luminescent swarms channel spell slots into healing others. Using spell slots for extra damage means that while blightbeast swarms can do roguelike damage, they lose steam quickly.
To make them a little hardier when area damage gets stronger at mid to high levels, they gain a form of uncanny dodge.
Also, to make them comparable to Moon druid high-CR forms at higher levels, Swarm druids have the ability to split into multiple swarms and replenish lost swarms at higher levels. I need to do further testing to see if having 2 to 4 swarms breaks action economy any worse than comparable conjuring spells.
Circle of the Swarm (Druid Archetype)
Combat Wild Shape
When you choose this circle at 2nd level, you gain the ability to Wild Shape on your turn as bonus action, rather than as an action.
The rites of your circle grant you the ability to transform into swarms of tiny beasts. Starting at 2nd level, you can use your Wild Shape to transform into a beast swarm with a challenge rating as high as 1 (you ignore the Max. CR column of the Beast Shapes table, but must abide by the other limitations there).
You cannot maintain concentration on spells while you are transformed into a swarm.
When you choose this circle at 2nd level, you also choose which kind of swarm you can change into: blighted or luminescent.
Blighted Swarm: While you are transformed by Wild Shape into a swarm, you can use a bonus action to expend a spell slot to inflict an additional 1d8 necrotic damage per spell slot expended on your next melee attack. The target makes a Constitution saving throw equal to your spell DC. On a successful save, the target takes half damage.
Luminescent Swarm: While you are transformed by Wild Shape into a swarm, you shed bright light in a 20-foot radius and dim light for an additional 20 feet. You can use an action to spend a spell slot to heal 1d8 damage per spell slot expended to an adjacent target.
Starting at 6th level, you can transform into a number of additional beast swarms up to your druid level divided by 6, rounded down. Each swarm must be identical, up to CR 2. Each swarm acts independently with its own actions. Reducing a swarm to 0 hit points does not cause you to revert to normal form, but it does kill that swarm. Only reducing all of your swarms to 0 hit points will cause you to revert to normal form.
When you revert to normal form, you can choose an unoccupied space closest to the remaining swarm of your choice.
Starting at 6th level, your attacks in beast form count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.
Beginning at 10th level, you can nimbly dodge out of the way of certain area effects, such as a red dragon’s fiery breath or an ice storm spell. When you are subjected to an effect that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.
Starting at 14th level, while you are in a beast swarm Wild Shape and have fewer swarms than your maximum number of swarms, you may expend spell slots to respawn swarms equal to the number of spell slots expended by 3, rounded down. You total number of swarms still may not exceed your normal maximum.
Common properties of swarms
- All have resistance to bludgeoning, piercing, and slashing damage.
- All are immune to charmed, frightened, paralyzed, petrified, prone, restrained, and stunned conditions.
- All can occupy another creature’s space and vice versa.
- All can only attack a creature in same space (0′ reach).
- All deal half damage when the swarm has half or fewer hit points.
- All can move through any opening large enough for a Tiny creature.
- All can’t regain hit points or gain temporary hit points.
List of Monster Manual swarms by CR
- Swarm of bats (1/4 CR, flying)
- Swarm of rats (1/4 CR)
- Swarm of ravens (1/4 CR, flying)
- Swarm of insects (1/2 CR) (plus variants)
- Swarm of quippers (1 CR, swim)
- Swarm of poisonous snakes (2 CR, swim)
- Swarm of flying snakes (2 CR, flying instead of swim)