Dealing with a tough enemy.....

[Necroticplague]

O.k, playing a game, and one creature's been giving the party way more trouble than it should. While it's stats and identity are unknown, I've figured out some of the larger trouble factors would like to see if the Playground can help me come up with something that might squash it.

1. It's a swarm of very small creatures. So anything that has a certain number of targets (and isn't mind-effecting) just flat out fails, and weapons are useless. Gonna need something that has an AoE.
2. Immune to mind-effecting. On top of this, it seems to be able to ricochet mind-effecting things, which leads me to believe it has deformity (madness) and insane defiance, and more importantly, covers up one of the Swarm type weaknesses.
3. Evasion. So most of the time, reverting to the default swarm-killers just ends up with it dodging.

The way I see it, if I want to actually kill this thing, I need some kind of area effect that isn't mind-effecting, and doesn't allow a REF save for half. Unfortunately, I'm usually a fighter-type, so my knowledge of what kind of spells fit this criteria is limited. I know of Hail of Stone, but that has an expensive material component and poor damage. Considered trying to trap them in an area where we can drop Walls of Iron on their hand over and over, but given the immunity to most forced movement (other than wind....that might have some promise). And their small size might let them justify them getting the save, rendering the exercise moot.

[Eldariel]

Well, speaking of wind, Control Winds or two to create a tornado (http://www.d20srd.org/srd/weather.htm#winds) would probably rip it to shreds in short order. Yeah, trapping it with Walls of Force or Stone or whatever is probably a fine solution. There's no real need to kill it and if you can trap it (Forcecage might work too), you can be on your way. Or just Teleport past it if killing it isn't essential. Alternatively, if it's vulnerable to Acid-damage, the game has a lot of AOE Acid-damage effects that don't allow saves: this handbook (http://www.minmaxboards.com/index.php?topic=9510.0) lists some. Trap it somewhere with one of those and it should go away. If Acid doesn't work, Limited Wish for Psychic Reformation and pick up the appropriate Energy Substitution. If none of the elements work, make it fire and metamagic with Searing Spell (again, via. Psychic Reformation if necessary). Alternatively, you could also gate it to the Positive Energy Plane: that place probably does the job for you. If you have the appropriate tools, you could also Planar Bubble the Positive Energy Plane to you.

Other options include figuring out if it needs to drink, eat, breathe or if it ages. If any of those are true, you can just trap it in a place where it lacks oxygen, sustenance or where it's aged at rapid pace. The way you put it though, there doesn't seem to be anything particularly problematic about trapping it. Create a Forcecage of some kind, make permanent if necessary and it probably won't escape until another hapless adventuring party comes to set it free. Most of this is about how to dispose of it afterwards if you feel like going through the trouble.

[Anthrowhale]

Earth Reaver(L5) does 4d6+3d6 no save. Iceberg(L9) does 20d6 no save. Frostfell(L8/L9) does 20d6 if they fail the fort save.

[legomaster00156]

It may be helpful to know the party composition and level, as well as the battle environment, and whether you have time to prepare.

[Eldariel]

Earth Reaver(L5) does 4d6+3d6 no save. Iceberg(L9) does 20d6 no save. Frostfell(L8/L9) does 20d6 if they fail the fort save.

Maw of Chaos likewise does Xd6 where X is caster level (uncapped) at no save, though it doesn't affect creatures with the Chaotic subtype. It is a level 9 spell as well.

[Morcleon]

Any AoE psionic energy power can deal AoE cold damage with a Fort save for half, dealing (maximum) 1d6+1 cold damage per ML.

[Extra Anchovies]

Swarms take +50% damage from splash weapons, so those could help. If store-bought alchemist's fire and acid flasks don't put out enough damage, see if you can make friends with an Alchemist (assuming you're in Pathfinder).

[Crake]

An enlarged, maximized, empowered acid fog would hurt, but then, that would hurt anything haha. Plop it in the middle, and they need to move 40ft to escape, but can only move 5ft/round, so at minimum 8 rounds inside, meaning at minimum 16d6 maximized and empowered, no save, no SR.

That said, if the swarm happens to also have acid resistance, even a small amount will be a huge reduction in damage, since the damage is applied every round in small ticks, rather than one big burst.

[Zaq]

Is it actually using the capital-S Swarm rules? Depending on how much HD this thing has, it sounds like Cloudkill might be useful.