How would I as a DM create a smart phone-like spell/device my players could use?

Question

My players are setting up a large nexus of guilds from my empire and one or two they made up themselves across several cities. They are having a hard time sending long messages to and from each other, and hiring a mage is not an option.

How can I, as DM, set up a multi-use system for them to send maps, long messages, money, basically anything small to and from places a few hundred miles apart fairly quickly?

I'm looking for a way to homebrew a device that can send and receive the things listed above from wherever my players are in the world.

Answer 1

Speaking stones

Speaking stones (WGtE, p. 44) allow for repeated long-distance communication. The stones allow for the holder to send a short message to any other speaking stone. [H/T Ryan Thompson]

Galder's speedy courier

The Galder's speedy courier spell (LLoK, p. 57) allows for instantaneous long-distance transport of small items. Adding the ability to cast Courier to the Speaking Stones from above should allow for limited transport of the required items. Longer or more detailed messages can be written and included in the courier.

Modifying the restrictions of the above to allow for use at the desired frequency and carrying capacity and you should have a (mostly RAW) network of devices that fulfills your needs and assists your players.

Answer 2

Unearthed Arcana Artificer makes something for this

If you're open to Unearthed Arcana options, the Artificer is able to use their ability to create the Many-Handed Pouch. This seems like an excellent option, although you may need to deal with the fact that the Artificer who creates it can't infuse anything else as it would create the end state of the item (see below for full description):

The infused pouches all share one interdimensional space of the same capacity as a single pouch. Thus, reaching into any of the pouches allows access to the same storage space. A pouch operates as long as it is within 100 miles of another one of the pouches; the pouch is otherwise empty and won’t accept any contents. If this infusion ends, the items stored in the shared space move into one of the pouches, determined at random. The rest of the pouches become empty

There are some potential issues regarding this item, so I'd definitely take a look at some of the other questions here about them so you're aware.

Answer 3

Relatively low-level option: Animal Messenger

The 2nd level spell Animal Messenger, when used on a flying creature, can send a long-distance message, and if the animal is friendly and well-trained, it can easily carry a small bit of cargo, like a document or a small pouch of coins. Of course, there is a real-world precedent for this in using homing pigeons to send messages.

Unfortunately, when cast at the base level, the messenger can only travel 50 miles, so in order to get the distances you're looking for, it will probably be necessary to cast it using a 3rd or 4th level spell slot, increasing the range by 100 miles for each additional spell level. Alternatively, it wouldn't be impossible to set up relay outposts every 50 miles along the roads between cities where low-level casters are stationed who can cast the spell at 2nd level as a ritual all day long, continually forwarding many messages per day. This would be a bit like a telegraph network.

The main advantage of this approach is that you don't need to acquire any magic items. However, you will need to acquire the services of either several mid-level casters (around 5th to 7th level to cast 3rd-4th level spells) or multiple low-level casters (3rd level to cast 2nd level spells), and you'll need to train a bunch of homing pigeons, which may or may not be easier than acquiring a pile of magic items depending on the setting.

One important limitation to keep in mind is the speed of messages: 50 miles per 24 hours. This means it will take several days to send a message a few hundred miles. This is probably fine for most day-to-day guild business, especially considering that all other mundane communications are similarly limited. However, it may not be ideal for emergencies.

Answer 4

Three new magic items from the Acquisitions Incorporated book

Three new magic items from the Acquisitions Incorporated book (an official WoTC published book) - the Documancer's Documancy Satchel, the Secretarian's Sending Stone, and the Hoardsperson's Living Loot Satchel - all seem to suit your requirements well.

The Acquisitions Incorporated source book is designed with the idea of joining, or setting up, a corporation in a D&D world (it's written to be specific to the Forgotten Realms, but could easily be adapted to any setting).

Documancer's Documancy Satchel

At rank 2, your documancy satchel becomes a common magic item, allowing you to magically send and receive documents to and from Head Office through a special pouch. Your documancy satchel magically produces pre-written and signature-ready contracts at your request, covering most common contractual needs. It also occasionally produces sticky notes printed with useful information and inspirational quotes from Head Office.

Secretarian's Sending Stone

At rank 1, you are given use of an Acquisitions Incorporated sending stone, an uncommon magic item that resembles a gemstone in a bold setting. It functions like a normal sending stones; sending stone, except that it has no matching stone, and allows communication with head office, specific secretarians you know, and the secretarian nearest your location. You must succeed on a DC 15 Intelligence (Arcana) check to establish contact. once the stone is successfully used it can't be used again until the next dawn.

Making contact with another secretarian assumes that they are in possession of their own sending stone

Hoardsperson's Living Loot Satchel

As a rank 2 hoardsperson, you are granted the use of a living loot satchel, which is an uncommon magic item. It functions as a bag of holding and is available in a variety of colors and styles.

[...]

The living loot satchel is a kind of magical being that safeguards the franchise's funds and valuables. It's innards are connected to a secure coffer within Head Office in Waterdeep, to which the satchel periodically transfers the franchise's wealth. As an action you can transfer any amount of your franchise funds back to your satchel with a successful DC 15 Dexterity (Sleight of Hand) check.

Each of these items has additional functionality granted to it as the owner ranks up within Acquisitions Incorporated, but their basic functions would seem to cover your needs to a tee.

Answer 5

As an alternative to Animal Messenger, you could instead use paper birds. From fandom:

After writing a small message (of 50 words or less) onto a paper bird, the sender whispered the name of the intended recipient. This caused the paper bird to magically fold and seal itself and to take flight, taking the most direct route toward the recipient at a top speed of 8.1 mph (11 km/h). Upon arrival at the proximity of its intended recipient, the enchantment wore off and the paper bird became a regular piece of parchment.

Paper birds were usually found in small boxes containing between 4 and 9 units.

Answer 6

Does it absolutely have to be a magic device?

There is a low tech solution for communicating between the guilds. Players could build a network of semaphore stations to communicate messages across hundreds of miles, as France did in the 18th century. Surely the Empire would take an interest in setting up a communication network and therefore the Emperor might be convinced to help foot construction costs in exchange for being allowed a portion of the communication "bandwidth" in the stations. :-)

As far as transporting money between guilds, why not invent a financial instrument instead of a magical instrument? Historically, promissory notes or banknotes (i.e., paper money) were used in ancient China and medieval Europe instead of physically transporting money between locations. If every guild has a cache of gold & silver coins, then Guild A could send a coded message to Guild B via semaphore that promises B a quantity of gold coins. This claim is then written on parchment and authorized with stamps or signatures, giving Guild B (or actually any holder of the note) legal claim on said quantity of gold in Guild A. If the guilds have a solid reputation for always paying their debts, and travel between cities in the Empire is reasonably safe for note holders wishing to cash in their note, then the promissory note could be used as money.

Answer 7

This is possible using the magic mouth spell as described here:

http://www.giantitp.com/forums/showthread.php?539861-The-Arcane-Programmer-Guide-(-Official-Rules-Technique-)

Would be a fun idea of build a campaign around if your party was so inclined.

Answer 8

It seems that teleportation would be a good choice here. Simply cast Teleportation Circle in all of your guilds/kingdoms and then either use more castings of TP to travel or use a Teleport.

Note:
For short messages Sending should work and you could give them/allow them to make a Helm of Teleportation if they don't feel like burning a 7th level slot every time they need to send a physical item.