Delwar swung his mace over and over, the end matted and bloody with goblin viscera and hair, but still the greenskins came after him and the rest of his team. It seemed like there would be no end of them, until they just about vanished. No magic there, just goblin cowardice. He gave a laugh and a shout, rallying Delwar's Devastators and sending them to chase the routed goblins. The gave a short pursuit not noticing they had charged into a goblin trap without even having the sense to see it coming.
Rothburn screamed, throwing away her ax to flail her arms at some unseen foe. Pit and Asheld followed suit, with the younger Pit fleeing, while Asheld prepared a fire spell and it fizzled out while he was struggling with some unseen assailant. Delwar swung his sword, invisibility spells? invisible stalker, air elements? He thought he was prepared until they were swarming over him.
Hundreds, thousands of spiders.
It all suddenly, horribly, made sense.
The Swarm Stump
It looked like any rotten tree stump you'd find in a forest, or on the edge of a field. Totally normal. There were a dozen found in the area where Delwar and his band of marauders vanished. The Devastators had made the decision to not hire a local guide, so didn't know about the stumps. They were trees once, but the goblins have their own magic, just like we have ours. They don't call thunder and lightning, or summon flame eagles. They are closer to the crawling things, to insects and noxious creatures. That's what the stumps are, they are breeding fortresses for swarming things.
Any local guide would have prepared them for this.
A Swarm Stump is a semi-ambulatory wreck of a tree, hollow and filled with rot on the inside, and offering a perfect place for spiders and insects to nest and breed in fantastic numbers. The method of creation is a goblin magic feat that relies on their innate gifts. It is speculated that a human or elf could recreate the spell to create a swarm stump using variations on the Animate Object spell, in conjunction with a Summon Swarm spell.
Game Notes: A swarm stump is a slow moving animated object. It has no attack, and is functionally a rotten stump. A few swings of an ax will bust it, but arrows, and other piercing weapons are less than effective. A small stump can hold one swarm of loathsome creatures, typically enough to swarm a single person. A medium stump has up to three swarms worth, and a large stump can have as many as ten. The swarms contained within a stump are all the same type, though different stumps in the same area can have different swarms.
Fleas - irritant, causes itching and distraction. Poor rest, reduced ability to resist illness and disease, and can carry specific targeted diseases, such as mundane plague to more colorful Goblin Pox or Swamp Fever.
Spiders - poison, possibly serious poison, bite for minor damage, cause fear and panic
Flies - obscure vision, carry diseases and can foul supplies and food.
Wasps/Bees/Hornets - painful stings, poison, possibly serious poison, just major bastards.
GM's Note: For best use, if there is a particular insect of other swarming type critter your player has a strong personal dislike of, that's the best thing to put in a swarm stump.
Tactics and Strategy
The Swarm Stump isn't intended to be a PC killer. It is a deterrent, something to slow them down or cause them to be more prepared than they need to be. Getting rid of a swarm stump isn't terribly hard. A basic fire spell cast on a stump BEFORE it launches it's swarm with destroy 1 swarm per round of burning. Small stumps can be charred in a single action, while a massive stump might have to be burned for over a minute to kill everything inside of it. An improvised molotov cocktail will also work wonders with a swarm stump. Vials of poison, gas attacking magic spells, and anything with an area based attack can eliminate swarms, but the character being swarmed is also subjected to the attack as well.
Illnesses and poisoning can delay a PC band, or send them back for healing and preparation. Ruined supplies, full of maggots and flies, can force PCs into hunting/foraging situations, or again, send them back for resupply.
The ambulatory nature of the stumps allows them to 'sneak up' on PC bands while they sleep. Stumps are natural lurkers and do not aggressively attack, they just have an uncanny sense of how to get in the way, where their swarms will be sure to go after something.
Greater Swarm Stumps
The basic Swarm Stump assumes a mundane swarm inside of it. Greater Swarm Stumps contain not normal insects, but enhanced insects. Sample ideas include elementally aspected insects that deal non-basic damage (flaming fire ants, stun gnats, spiders with wings, etc) Greater Swarm stumps can pose a serious threat to low level characters, killing henchmen, livestock, and the unwary and unprepared.
Superior Swarm Stumps
These rare stumps are carved in the likeness of learing faces, with branches shaped like arms. They are all large stumps, and hold as many as twenty swarms and are always filled with the worst sorts of swarming creatures, such as abyssal blood flies, or acidic hornets. In addition to launching swarms of insects, the stump can batter with it's branch arms, and laugh hideously at the predicament of the fleshies.