Conjuring this with the conjure animal spell remembers me of Dishnored so much! Maybe I will make a magic item inspired in it: it would be a flute made out of carved whale bone that could conjure 2 or 3 rat swarms

Hey
I actually made up such flute as an uncommon magic item.
In my game it can summon up to 6 swarms (6 charges, recharge 1d4+2 on dawn) by using an action.
Flute of Hamelin, named as in legend, is used by team's bard and works great as crowd control.

Pipes of sewers

dude have you ever hear about the pipes of the sewers, an magic item in the free that does exacty that?

you know what? here click here and read it for yourself

oh, you mean almost exactly like this already existing magic item from the dungeon masters guide?

Yep … my Bard has one … very useful!

My lizardfolk just found the pipe of sewers should I use my downtime days to get it

Quote from davidbowen >>

My lizardfolk just found the pipe of sewers should I use my downtime days to get it

 

 

 It does sound kind of cool, especially if he’s a nature or city-attuned character.

This is a real thing. If rats get stuck together, after a few days they develop a hive mind. The only inaccuracy is calling it “Swarm of Rats” and not “Rat King”.

 Idk if my druid is allowed to become a swarm of rats but I'm doing it anyways 

Have you ever thought that if they can accompany the same space, does that mean i can have a tower of 30 rat swarms

Quote from Elvimore >>

Have you ever thought that if they can accompany the same space, does that mean i can have a tower of 30 rat swarms

 There is curse of stradh encounter that does that.

Quote from NeverPlayedJustStalks >>

Conjuring this with the conjure animal spell remembers me of Dishnored so much! Maybe I will make a magic item inspired in it: it would be a flute made out of carved whale bone that could conjure 2 or 3 rat swarms

 You cant use the spell to conjure a swarm, you can only use it to call forth multiple animals but never a swarm. 

A Rat King is different to a swarm of rats. A Rat King is a group of rats that are physically stuck together; usually by entangled tails. A swarm of rats is just a large group of separate individual rats. It's like a replacement for keeping track of 100 individual rats in combat.

Quote from Aurell >>

Quote from NeverPlayedJustStalks >>

Conjuring this with the conjure animal spell remembers me of Dishnored so much! Maybe I will make a magic item inspired in it: it would be a flute made out of carved whale bone that could conjure 2 or 3 rat swarms

 You cant use the spell to conjure a swarm, you can only use it to call forth multiple animals but never a swarm. 

Based on the hit dice, if you could summon 14-to-24 rats, I suppose then they could Swarm.

How many rats do you think are in a swarm of rats? 10? 20? Over 100?

Quote from PMFL >>

How many rats do you think are in a swarm of rats? 10? 20? Over 100?

 My guess is some multiple of 24 (7d8-7).

rats (:

When swarms first came out, in 3.x, they were immune to slashing, piercing, and bludgeoning.  The only way to kill them was with fire or acid or AE damage.  

That makes sense since it's not one creature but dozens of little ones.

So when my players hit them with, say, burning hands, how do I rule that the whole swarm takes 3d6 damage, rather than each individual rat taking 3d6 damage and the swarm dying immediately?

Eagerly await your response.