Tybalt: I'm not sure what glitterdust is going to do to a swarm. They could in theory be blinded, but they do not make attack rolls, so I am not sure that that will be a problem for them.
Res and Leandro swing their torches, and the tiny insects seem repulsed by the flames. It seems to be having an effect, albeit a modest one. They are immune to weapon damage, so it is only the fire that hurts them.
Andrzej's flask of fire has a more appreciable impact and leaves some of the insects charred. You can tell it will take more where that came from to make the swarm disperse.
Leandro: I am considering that attack your AoO. You still have a round worth of actions. Also, Tybalt, if you change your mind about the spell, you may do so.
Anuqa, Eliva, and Angalia are up.
Eliva blinks, holding her burning arrow in one hand, then rummages around in her pack, triumphantly pulling out a flask of green liquid. "I have this and one other - it might help!". She looks for something hard amidst the swarm to smash the acid flask against.
Leandro flails at the swarm from inside with his feeble torch but makes no attempt to escape the bloodsucking menaces. "Kill them!" he chokes, trying to veil his face with his arm for protection.
atk: 1d20 + 3 ⇒ (10) + 3 = 13
It's simply one point of fire damage if it hits, I guess. Let me know if you want a roll.
Eliva's voice is full of regret as she responds, "I have no oil. I have some healing magics to make this up to you, Leandro - my apologies!" At the last word her voice involuntarily harshens as she throws her first flask at the beleaguered paladin with all her strength and concentration.
Attack: 1d20 + 8 ⇒ (2) + 8 = 10 (touch)
Damage: 1d6 ⇒ 2
The acid seems to burn away some of the insects, and also some of Leandro's flesh.
Anuqa approaches and apologetically brandishes his wand, sending a gout of flame that engulfs both Leandro and the swarm of insects.
1d4 ⇒ 1 damage, DC 12 reflex save for half.
Swarm save: 1d20 + 6 ⇒ (2) + 6 = 8
The swarm continues to envelop Leandro in its cloud of crimson, as tiny gnats find their way into his arm and continue to bite at him.
1 more Con damage.
Reflex Save: 1d20 + 5 ⇒ (2) + 5 = 7
1 pt fire dmg, 3 pts acid dmg, and 1 pt Con since last dmg.
"Good! Keep killing them!" Leandro tries to encourage his friends while waving his little torch amidst the insects. "I used my oil on these torches, sadly." He spits more of the menaces on the ground between gasps for air.
torch attack!: 1d20 + 3 + 1 ⇒ (5) + 3 + 1 = 9
1 pt fire if it hits (Leandro is inside the swarm, so can it miss?)
Con damage: 2
Con penalty: -1
Fort save currently +9
HP loss due to Con = 5*1 = 5
Other HP loss = 5
The magus pulls out a flask of oil and lobs it onto the burning pool of gnomish fire. With a crump the mass detonates.
Oil flask onto swarm (AC5 to hit a square)1d20 + 7 + 1 - 4 ⇒ (7) + 7 + 1 - 4 = 11, damage 1d6 ⇒ 1 plus second round of alchemists fire 1d6 ⇒ 5, plus half (3) = 9 points of area damage. I doubt the bard bonus applies to this anyway.