fectin wrote:Source? I thought that was the case too, but went looking recently and couldn't find anything of the sort.
It's under the Swarm entry in the Types listing, either in the MM or the SRD, but not conveniently in the partial listing of swarm traits in the creature listing.
fectin wrote:It really can't. Bats "see" perfectly for 20 ft, and move 40. They either reach you fine or do nothing.
So you can defeat the swarm by being more than 20 feet away? It's moot in any case, because they're crisped by the breath.
fectin wrote:Are breath weapons spell effects, weapons, or missiles? Because that's the complete list of things that go through the walls. It's an opaque sphere of force with some weird interactions listed.
It is the complete list of things that go through the hut 'without affecting it.' Your reading is based on ignoring a chunk of the sentence.
'Sphere of force' doesn't mean anything except that it also extends onto the ethereal plane. Wall of Force isn't immune to damage and impassable because it's a force effect, it is those things because the spell description tells us it is those things.
Tiny Hut tells us what it stops, and one thing that it will not stop (and will be destroyed by). It then has a list of things that it will not stop, but which will not destroy it. The ambiguity exists, but it exists in whether or not the Hut survives contact with the breath weapon, not whether or not it stops the breath weapon.