[5e] Druid Circle of the Rat Swarm. Feedback needed

[Redthistle]

Thank you for your kind words.

I do see now the Problem with the poisonous Effects.

Vitriolic Explosion
At 6th level a druid in its swarm form can sacrifice up to 10% (rounded down) of its current hit points as a bonus action to cause 1d4 per Hit Die poison damage.
Some rats in the swarm are hit with an instantaneous mutation. Blisters and tumors rapidly grow on those rats, and on each round that the druid sacrifices 10% of its remaining hit points, those rats begin exploding, covering the target in gore.


if we change this part into:
At 6th level a druid in its swarm form can sacrifice up to 10% (rounded down) of its current hit points as a bonus action to cause 1d4 per sacrificed Hit Point poison damage. Once a creature is infected it can't be poisoned again.


If we take the suggested route of using Hit Die, the Subclass runs into a Problem with the variant Rules of Rest (Gritty Realism) DMG 267.

If you're running a Gritty Realism campaign, that changes my perspective, and you're right. Your modification here makes more sense. That 14th-level druid, sacrificing 11 hit points and doing 11d4 poison damage, is a lot more manageable.

Another consideration is that, beginning at 4th-level, a druid can wild shape into a Large creature, which covers 4 times the space that a Medium-sized creature does. A Large-sized swarm should be able to attack each creature in the space it covers. The swarm's size and number of attacks should be the only changes made to the Swarm of Rats as described in the Monster Manual.

If we specify that Vitriolic Explosion can only be used on one target per round, it still increases the overall effectiveness of the Circle feature.

As a Large swarm takes damage, each 25% reduction in its hit points should reduce its size by a quarter, and takes away one potential attack, until it is reduced to Medium size again.

Does that fit your vision for this Circle?

 

[Redthistle]

Hmm as the druid gets a modified swarm, at level two, that inherently grows in the hitpoint amount as well as in the number of attack die, an option could be to modify the swarms ability points so that it is in line with a big rat (increase the armor class by 2 and pump up dex to a +2 modifier). At level 8 we could give him the option to turn into pigeon swarm (maybe reskind raven swarm)

Pigeon Swarm! I love it! Some people describe them as flying rats anyway.

 

[prof_farnsworth]

As a Large swarm takes damage, each 25% reduction in its hit points should reduce its size by a quarter, and takes away one potential attack, until it is reduced to Medium size again.

Does that fit your vision for this Circle?

That sounds perfect, are you suggesting that the large swarm gets 4 attack actions per round? If so i would limit it to one attack per square. This gives the druid the ability to control the battlefield, without outclassing the melee characters in close quarter damage.


You mentioned that the druid could make a poison attack that hits for 11d4 at level 14. As i see it his swarm has 66(24+14*3) hit points. 10 percent of these hit points are 6.6; when we round it down it's 6d4 poison damage.