At some point, your characters may decide that they have had enough of hunting down monsters, killing them, and taking their stuff — at least for awhile. Back in 2nd Edition AD&D, this step in character development was somewhat formalized:
When a fighter attains 9th level (becomes a “Lord”), he can automatically attract men-at-arms. These soldiers, having heard of the fighter, come for the chance to gain fame, adventure, and cash. They are loyal as long as they are well-treated, successful, and paid well. Abusive treatment or a disastrous campaign can lead to grumbling, desertion, and possibly mutiny. To attract the men, the fighter must have a castle or stronghold and sizeable manor lands around it. As he claims and rules this land, soldiers journey to his domain, thereby increasing his power. Furthermore, the fighter can tax and develop these lands, gaining a steady income from them. Your DM has information about gaining and running a barony.
Standard Magic Items
A few magic items already exist which can aid in community building. A Decanter of Endless Water can provide clean water for hundreds of residents. A Cauldron of Plenty can help to feed the populace. A Lyre of Building can be used to construct homes, business, road, and fortifications. An Everburning Lantern can bring light to the darkness. Even a humble Robe of Infinite Twine can provide useful resources to the community.
Magic Items Created with the Permanency Spell
Many beneficial effects can be created with the Permanency spell. A Symbol of Healing can be set up in a central location to act as a first-aid station. Teleportation Circles can be built to enable efficient trade with distant lands. Animated Objects can provide manual labor. Wall of Fire can be used for heating. Mechanical power can be generated with Gust of Wind (windmills), Wall of Fire (steam engines), or Animated Objects (manual labor).
Crafting Custom Magic Items
The real joy of building your own community comes from crafting your own magic items. Here are a few suggested magic items for a magical community.
All items are priced with the standard (albeit broken) formulas:
Spell level × caster level × 1,800 gp x 2 (No space limitation) + 100x spell component cost
Spell level × caster level × 1,800 gp x 2 (No space limitation) / 5 (1 charge per day)
These costs should probably not be used. Instead, costs that make sense in your campaign should be assigned.
Altar of Amanuensis
The Altar of Amanuensis copies writing from one source (such as a book) to be copied into a book, paper, or parchment. This altar copies 250 words per minute and creates a perfect duplicate of the original. The altar only copies nonmagical text, not illustrations or magical writings (such as spell scrolls or a sepia snake sigil). If the target contains normal and magical writing (such as a letter with explosive runes), only the normal text is copied, leaving blank space in the copied text where the magical writing would be expected. Likewise, if the target contains text and illustration, only the text is copied. Blank paper, parchment, or a book must be provided for the spell to write upon.
Altar of Mending
The Altar of Mending repairs damaged objects, restoring 1d4 hit points to the object. If the object has the broken condition, this condition is removed if the object is restored to at least half its original hit points. All of the pieces of an object must be present for this spell to function.
Altar of Endure Elements
The Altar of Endure Elements enables the petitioner to exist comfortably in conditions between -50 and 140 degrees Fahrenheit (-45 and 60 degrees Celsius) for 24hrs.
Altar of Hauling
The Altar of Hauling causes a petitioners carrying capacity to triple for 2 hours.
Altar of Soothing
The Altar of Soothing causes several conditions to be lessened in severity one step. If the petitioner is nauseated, he is instead sickened. If he is stunned, he is instead dazed. If he is exhausted, he is fatigued. If he is frightened, he is shaken. If he is paralyzed, he is staggered. The duration of the effect is unchanged; the effect is simply reduced to the lesser version.
Altar of Truth
The Altar of Truth causes creatures within the emanation area (or those who enter it) to be unable to speak any deliberate and intentional lies. Each potentially affected creature is allowed a save to avoid the effects when the spell is cast or when the creature first enters the emanation area. Affected creatures are aware of this enchantment. Therefore, they may avoid answering questions to which they would normally respond with a lie, or they may be evasive as long as they remain within the boundaries of the truth.
Altar of Remove Disease
The Altar of Remove Disease can cure all diseases from which the subject is suffering. The petitioner must make a check of 1d20+5 against the DC of each disease affecting them. Success means that the disease is cured.
Altar of Remove Disease, Limited
Once per day, the Limited Altar of Remove Disease can cure all diseases from which the subject is suffering. The petitioner must make a check of 1d20+5 against the DC of each disease affecting them. Success means that the disease is cured.
Altar of Food
The Altar of Food grants each petitioner enough food to sustain three humans for 24 hours. The food that the altar creates is simple fare–highly nourishing, if rather bland. Food so created decays and becomes inedible after 24 hours
Altar of Healing
The Altar of Healing channels positive energy into a creature to wipe away injury and afflictions. It immediately ends any and all of the following adverse conditions affecting the Target: ability damage, blinded, confused, dazed, dazzled, deafened, diseased, exhausted, fatigued, feebleminded, insanity, nauseated, sickened, stunned, and poisoned. It also cures 110 hit points of damage. The Altar of Healing does not remove negative levels, restore permanently drained levels, or restore permanently drained ability score points.
Altar of Healing, Limited
Once per day, the Limited Altar of Healing channels positive energy into a creature to wipe away injury and afflictions. It immediately ends any and all of the following adverse conditions affecting the Target: ability damage, blinded, confused, dazed, dazzled, deafened, diseased, exhausted, fatigued, feebleminded, insanity, nauseated, sickened, stunned, and poisoned. It also cures 110 hit points of damage. The Altar of Healing does not remove negative levels, restore permanently drained levels, or restore permanently drained ability score points.
Aspergillum of Plant Growth
The Aspergillum of Plant Growth effect targets plants within a range of a half-mile, raising their potential productivity over the course of the next year to one-third above normal.
The Fabrication Machine converts material of one sort into a product that is of the same material. Creatures or magic items cannot be created or transmuted by the Fabrication Machine. The quality of items made by the Fabrication Machine is commensurate with the quality of material used as the basis for the new fabrication. If you work with a mineral, the target is reduced to 1 cubic foot per level instead of 10 cubic feet. The Fabrication Machine cannot fabricate articles requiring a high degree of craftsmanship. The Fabrication Machine requires 1 round per 10 cubic feet of material to be affected.
Fountain of Holy Water
The Fountain of Holy Water imbues a flask (1 pint) of water with positive energy, turning it into holy water.
Hitching Post of Mounts
The Hitching Post of Mounts summon a light horse to serve as a mount for 2 hours. The steed serves willingly and well. The mount comes with a bit and bridle and a riding saddle.
A Word About the WBL
These items tend to be expensive, but they do not directly affect the power level of the characters. As such, if you use the WBL guidelines, a good houserule is that only a small fraction of the value of these items should be counted against the characters WBL limits.