Elmelio's sling bullet struck in the center of one of the swarms. Singular strikes against a surging mass of tiny creatures weren't highly effective, but nonetheless he squished a few of them and set a few more scurrying away from the larger swarm.
Ember still wasn't quite able to make out what the others had seen, but he knew where they were. He wasn't quite lined up with the first group, but the electricity shocked through the second. They were quick, and scattered around the blast, but it still left some dead centipedes.
Malcolm and Mezzaline's discordant music burst through the entire mass.
As one group converged on Saoirse, it seemed already to have lost nearly half its number already, twitching under the fallen tree. The other half of the centipedes, though, charged forward as those Mezzaline's spell had no effect on them. These swarmed over Athraz.
A centipede is normally no real danger to a person. Even if they should manage to bite, the tiny pinprick is harmless and the dose of venom ineffectual.
In this number, though, the mass of creatures crawling all over the two adventurers had the strength of sheer numbers. Both Saoirse and Ahtraz felt tiny needles all over their bodies, and dozens or hundreds of tiny doses of venom threatened to overwhelm them.
Loading a sling does indeed cost an action, but I'm cool with assuming you had a weapon ready. Elmelio hits and deals some damage after resistance.
Is that a typo? Your spellcasting DC is 19, Ember, not 10. Ember fails to target one, and the other succeeds on its save.
Haunting Hymn affects an area, so you can both get both. Could you both include your spell DC and damage in the future, though? Against Malcolm's spell, the first succeeds and the second fails. Either way, they take extra damage from weakness to area damage.
Against Mezzaline's, the first succeeds, but still takes enough damage to reduce it to half HP (shorthand as "Bloodied on the Status page). The second critically succeeds and takes no damage.
I should... definitely get a map up. I suppose, since the lack of map is my fault, it's only fair to assume you're spreading out.
Swarm A Strides into Saoirse's space and uses its Swarming Bites twice.
Friendlier damage rolls this time--4 and 2--but the saves are the same for you--DC 20 Reflex for each damage roll, and Fort save against venom if either Reflex is a failure.
Since they moved out of their hiding place, everybody knows where they are now.