Get Your Ass in the Dungeon

Donkey mini from Otherworld Miniatures (they have 4
variants).  You'll need to put them on a medium base.

Eventually, a Pathfinder player will want to bring his jack or jenny (male or female donkey) into the dungeon. It makes sense. The basis for this desire is the explanation of how these animals behave in the game:

Donkeys and mules are stolid in the face of danger, hardy, surefooted, and capable of carrying heavy loads over vast distances. Unlike a horse, a donkey or mule is willing (though not eager) to enter dungeons and other strange or threatening places. Donkeys and mules have the same statistics as ponies.

The mantra for the donkey is "donkey don't care." Faced with danger, dungeons, strangeness or heavy loads, the donkey does not care.

The key then, is getting your game master on board with the use of livestock in their dungeon. The donkey has been bred as a pack animal for difficult situations for 5,000 years in the real world, so there's no reason it should seem inconceivable in a fantasy setting. Assuming you have honorable intentions, and aren't looking for an extra combat advantage with a cut rate guard dog replacement, the simple question of "Are you gonna mess with my donkey?" should start that conversation.

The Objective Facts

The donkey uses stats borrowed from the pony. That, first and foremost, means a donkey is a medium sized creature. Size is critical, because a large creature in a dungeon is difficult to manage and tends to become a nuisance. A medium based donkey is ideal for a caster, especially a wizard, who tends to stick in the back, avoiding harms way. You can't really manage a donkey remotely (see Handle Animal below), so it's not a great fit for melee characters. Donkeys also don't make the list of familiars or animal companions.

Encumbrance: The donkey has a light carrying capacity of 75 pounds, which allows it to move its full speed of 40. At the next level of encumbrance, 150 pounds, it moves at 30. Bumping that up to 225 pounds doesn't change your donkey's speed, so that's roughly your target (beyond 225 pounds your donkey can't move). You will encumber your donkey to some degree, because there is no food in the dungeon and the donkey must carry it in. Claiming the donkey eats grass and such outside is fine (donkeys have a far more robust gastrointestinal system than horses), but in the dungeon you'll need to hoof in the bags of feed it must consume (more than likely a big 50 pound bag like the one below).

Food is 10 pounds per day, so a week of food is already half his unencumbered weight. My ideal donkey weight is right under 225 pounds, so he's encumbered, but still moves at 30 like most of the average adventuring party. Medium and Heavy encumbrance are both going to knock the donkey speed down to 30 from 40, so load him up to Heavy.

Loading up your donkey with his own provisions, is going to be much of what the donkey carries. Beyond that, you can grab from an enormous list of equipment you would rarely bother with, but might come in handy or add flavor to your character. This is inexpensive and useful at low levels, but loses its charm once you can afford magical bags and the like.

For example, here's what my donkey is carrying:

Air bladder, ale (gallon), animal glue, block and tackle, bread (2), bucket, candle (10), canvas (sq. yd.) (5), chalk, cheese, coffee (per cup) (16), coffee pot, earplugs, feed (per day) (7), firewood (per day), folding pole, grappling hook, grooming kit, honey (per jar), meat (3), mess kit, miner's pick, mug/tankard, oil (7),  pack saddle, piton (2), pot, saw, scrivener's kit, shovel, silk rope (50 ft.), skillet, survival kit, tea (per cup), torch (3), trail rations (14), travel cake mix, twine (50'), waterproof bag.

HeroLab is your friend when it comes to this type of fun/tedium. I've got a bunch of useful dungeoneering supplies along with flavorful items like pots and pans and cake mix. You can certainly live off trail rations, but why not bring some firewood and bake a cake? The total value of this gear is 52gp, and along with 8gp for the donkey, the total replacement cost is a measly 60gp. You could do this at first level with many characters.

Of course, the most hopeful reason to bring a donkey into a dungeon is to carry out vast quantities of loot. Although, the GM is more likely to ding you on encumbrance on your way in, it's nice to have a means to justify your loot carrying capacity on the way out. If nothing else, your donkey can carry the corpses of your fallen companions. As your donkey consume donkey chow, you'll be making room for your inevitable success ... or failure.

Handle Animal: "But what about the Handle Animal skill," you ask? If you're not going to command your donkey to perform a task or push it to do something it doesn't normally do, then you don't need it. Assume the stalwart donkey goes wherever you lead it, on the lead. When you're not leading it, it stands there.

Combat Training: This is not a combat donkey, something to stress to your GM. However, it is safe to fall back on your mantra of "donkey don't care." Combat won't startle or spook a donkey, but neither is the donkey likely to attack unless attacked first. Donkeys were used in WWI by Italian fusiliers to carry their gear, so if modern combat won't spook a donkey, some measly kobolds certainly won't.  As an aside, the donkey was used for food when stores were low, adding one more use for your donkey.

Skills (really Perception): Your donkey has a +5 Perception check. Part of "Donkey don't care" will likely be donkey don't care about Perception checks. If there's something especially disconcerting, your donkey won't communicate it, but might become fidgety or balk when entering an area.

Perception is your only donkey skill of note, and with encumbrance, every other skill on my donkey is zero or worse.

The Subjective Facts

Some basic donkey research reveals a few details:

Animal Relationships. Donkeys and horses get along splendidly, unlike the stories you hear about say, horses and camels. They can interbreed in fact, if you want a little dungeon drama. Donkeys will protect herd animals like sheep by stomping smaller predators, like wolves. Donkeys do not get along with wolves or dogs, and it's safe to say they'll donkey stomp anything small that threatens them. 

Eating, Pooping, Sleeping: Donkeys eat a lot and poop when they eat, so you shouldn't expect donkey scat scattered around the dungeon. Donkeys also sleep lying down, preferably in a clump of hay you've just tossed down for them. Expect to unpack and pack your donkey each day, if such details matter to you.

Stairs. Donkey don't care. Watch videos of tourists riding donkeys down vast stairways in the Grand Canyon. Assume donkeys can manage difficult terrain without trouble.

"Donkey don't care" really sums it up. Sure, a donkey is quickly outperformed by even the lowest level, Type I, Bag of Holding, but that should reassure your GM that you're not trying to get away with anything. An 8gp donkey versus a 2,500 gp magic items certainly seems like a bargain to me.

Spyridoula

Nobody has ever survived the night in the Three Valleys Bog.

Until now.

Attacked by waves of zombie hordes, the party's tiny hut was eventually overwhelmed. Not just a bunch of zombies, but hordes of them bit, scratched and pulled at the heroes, at one time slaying the lizardfolk rogue before the druid finally had them under control on a variety of fronts.

Before the attack, the Heroes of Tara discovered standing stones. In fact, they discovered a number of them, in what was later determined to be a semi-circle.

Each set of stones were carved with the cyclops princess Spyridoula and her devotions to her hounds. The monoliths formed a circle, with cross members linking them to a central pillar and a statue of an angry cyclops, it's mouth open in a roar. It was determined that hot air was venting out of the mouth of the statue, smelling of peat.

As the party searched further, the discovered additional standing stones every few miles, usually situated in an especially boggy location.

As the undead roamed the land when the sun fell, something else peculiar was going on. One in five of such hordes was a work party. They would dig up peat moss in big clumps and leave it to dry, but also taking dried peat from what was likely previous evenings. They all headed back to the center of the circle formed by the standing stones. Here they heroes discovered some sort of funerary building.

Additional undead could be seen coming and going from the building, including quite a few "free willed" undead, like spectres and talking zombies and skeletons (lords more than likely). Atop the building was peat and other bog debris, dripping down the side, as if the structure had just emerged from the bog itself.

This is more than likely the Tomb of Spyridoula, legendary guardian of the cyclops people, who they say gave her life to defend the island from revolting humans.

Four Streams

This druidic site is perpetually shrouded in fog as it sits on a small hill in the middle of a bog. The bog is the site of an ancient battlefield, a long running war between the cyclops and man.

The site is surrounded by a tall, wooden, circular wall with a small path leading up to a door. Inside the structure, in the center, stands a giant, four sided obelisk. Various runes and writings cover the obelisk, but rather than usual druidic script, the inscriptions are even older, thought to be the writing of Mannanan Mac Lir himself. Or as the caretaker, Pholus, refers to him, The First.

A pathway surrounds the obelisk and winds around it, sloping upwards as it spirals around. Off the path are various dwellings, and although only Pholus lives here now, it's possible to conceive of a large village once calling this home.

 The obelisk appears to tap directly into the elemental planes, based on the runes inscribed upon it. Activating it controls weather in a 24 mile (four hex) radius. Each additional standing stone controlled, increases the radius by an additional 6 miles (one hex). Activating the obelisk is risky, as the electrical charge projecting the magic is unstable. Pholus also speaks of a key required to use the obelisk, a key he'll provide once his quest is fulfilled.

There are no standing stones here, nor does Pholus believe there to be any in the Three Valley region.

Tower of Sakarbaal

Centuries ago, the wealthy Phoenician wizard-merchant Sakarbaal traveled to the Island of Redstone after hearing of the rumor of a Font of Youth. He brought his young apprentice. The boy knew he would not see his family again and might spend the rest of his short life in the wilderness with his old master. They sailed the long distance in the wizard’s opulent ship and traveled to cyclop ruins in the north, where they found The Machine of Creation, rather than the secret of youth the wizard desired.

Sakarbaal had an idea for his immortality. What if he could make the Font of Creation create a permanent, infinite plain instead of demiplanes? He could populate this realm with followers and achieve immortality through godhood! But such a plan would require enormous, near infinite power.

He carefully removed the artifact and brought it another site he had investigated, The Sea of Grass, where he recalled standing stones in the middle of nowhere on a planar conjunction to the ethereal plane, the plane of creation. He sold his ship to pay the cost of re-installing the artifact directly in the circle of stones, and over the years, found a way to tap the standing stones to power the artifact in an
infinite loop of creation.

The Tower is constructed of stone with a metal skin on the outside made from plates of Umbrite, which cloaks the tower in shadowy darkness, extending out into the lake. As Sakarbaal was about to realize his dream, the forces of nature revolted and performed rituals to bypass his source of power along the ley lines. Nature would not be hijacked for the sake of one man’s immortality. Life within a mile was destroyed and the artifact was badly damaged. The artifacts destruction resulted in a dweomersink in the area. The machine sucked the natural energy from where it sat, creating a ground sink that eventually filled up with water. The bottom two levels are now completely submerged,
and a lake has formed around the tower.

An arcanoplasm dwells in the lake, feeding on the residual magical energy and anything that stops by.

His assistant, who wished to obtain immortality with Sakarbaal attempted to turn himself into a lich, and failed. He’s also here.

Also see The Annals of Denbacan for more about Sakarbaal's quest.

The Three Valleys (History)

Around 1,000 year ago, the Axial Age was at its height. The cultures of the Yan Ki, Northmen, Phoenicians and Early Men reached maturity, right as the Cyclops civilization began to fall into disarray. Such high cultures could agree on one thing, slavery at the hands of the Cyclops could no longer be tolerated.

The center of Cyclops civilization was Redstone Island and the region most contested was the bogs of the Three Valleys region. Here, the Early Men made their home and the Northmen held sway. The Cyclops were hindered by the mountains protecting the Three Valleys, which made it difficult for them to defend it. Thus. many battles were fought here and the Cyclops made it a point to leave their mark so there was no confusion who was in charge.

Dozens of Cyclops standing stones were placed in the bog region, a show of their power, but otherwise not of magical significance. It's also said, the Cyclops lich, Thunderer, made his home somewhere in the valley region. Undead began appearing shortly thereafter, to the point nobody has ever survived the night in the open in the Three Valleys.

Towards the end of the Axial Age, the Battle of Three Valleys took place. The Northmen General Habgard had build a wall defending the region from the Cyclops. The Cyclops breached the wall, defended by the Northmen and Early Men warriors. In an act of betrayal, the Northman leader now known as Bloody Erik, allowed the Cyclops through to decimate his Early Men allies. He believed The Northmen would one day take Redstone Island and eradicate the native inhabitants, a view that it was later learned he received from his spiritual guide, the Cyclops lich Thunderer.

The Three Valley region remains in turmoil today. Slavers and goblins harass the Early Men tribes. The Early Men civilization is long gone and they hide in the cracks of the earth from their enemies. Undead run rampant through the region, with different groups acting in different ways. Those in the north of the region only come out at night, killing and dragging off their victims. Undead from the south rampage at all hours, often kidnapping who they find. The red dragon, Flameworm, considers everyone in the valley a trespasser, including the forces of Crannog. The druid Pholus works to maintain a balance, although his feud with Flameworm often keeps him gone for long periods. It is the chaos of the Three Valleys that keeps Tara safe from invaders from the east of the island, but that safety may end one day soon.