Skywrite, The Magical Telecommunication Network

or

How I Got Skywrite Banned From Your Game

Skywrite is a crazy spell. It is a 2nd level spell that appears on the Bard, Druid, Wizard and Artificer spell lists (and possibly accessible for some Warlocks and characters with the Ritual Caster feat). For starters, it is a Ritual which means many casters can perform it without expending spell slots, and with no material component (valuable or otherwise). And then there is that range of “Sight”, specifically “…in a part of the sky you can see.”. Let’s nail this bit down before going further because it opens up some world-changing potential for a creative DM or Player.

You’ll hear people quote wildly different numbers for the distance of the visible horizon without a lot of explanation for those numbers. I often hear a range of anywhere from 3 to 60 miles quoted, but the actual distance is a bit more situational. A deep dive of the math can be found on the NASA site, but the short answer is “it depends on the elevation of the observer”.

• 6′ tall person on a flat landscape = 3 miles
• Standing on top of Mount Everest (5.5 miles) = 230 miles

These values above aren’t quite what we need, though, since they are actual measure how much of the planet’s surface an observer can see by accounting for the curve of that planet.

From the point of view of a terrestrial viewer, the sky appears to be a dome so you are not comparing two points on the same sphere, but one point on a sphere (the planet) and another positioned on a sphere (the sky) around that inner sphere. In fact, if you want to argue about the definition of “sky”, with 20/20 vision you can see objects upwards of 2.25 million light years away (Andromeda Galaxy) on a clear night which would make that second sphere visible from practically any part of the hemisphere your sender and observer share (sorry, no North Star for you, Australia). We are not going to argue that though, because that way lays madness.

We’re going to stick with a definition that makes more sense to a medieval magical/fantasy world and is more in keeping with the spell’s description, clouds. Unless your world is very odd, that is probably going to max out at 50 miles up.

So how far away could a 6′ tall person standing on land, project their message into the sky?  We use the formula for “line of sight” radio transmissions!

Answer: Pretty damn far! Assuming your planet has no mountains higher than Mount Everest, about 685 miles away. This makes the message potentially visible in a cone roughly 685 miles in every direction from the point it is placed in the sky.

You have just created a messaging system which can relay short messages, quickly, across a landmass approaching the width mainland Europe. This is huge. The inability to communicate and administrate over long distances contributed strongly to the collapse of numerous large, pre-modern civilizations. You’ve overcome it with a 2nd level spell!

So about that “short message” part. The spell’s description says “up to ten words”. If the “Common” tongue of D&D is anything like Earth languages, this could average anywhere between 7-12 characters. Making your message roughly on par with a short tweet.

But what about security?

Writing non-sense words (as long as they still observe the word count and reasonable character length), you could transmit completely encoded messages.

Alternately, the spell is not limited to any particular language, so obscure or constructed languages might be an option. Comprehend Languages would not help in these cases, since it is unlikely viewers would “be touching the surface on which the words are written”.

Another option in keeping with the spell’s strict description would be to have authorized persons use a prearranged glossary where words representing entirely different meanings, allowing them to create sentences of seeming gibberish, constructed of real words:

autumn calico marmalade foster lucid hat measurement vintage scholar

retreat helms deep reinforcements from east dawn fifth day

You could further increase the information density of your messages by having certain words represent prearranged messages that you know you are going to need to send frequently.

Yes, yes, this is all “under optimal circumstances”. If your world is plagued by a perpetual cloud layer hovering just 10 miles up, the “visibility cone” would drop to ~600 miles diameter, for example. Still quite respectable. Additionally, other local conditions might mean having to wait for a window of opportunity to send messages, but the spell is a Ritual and can be attempted again roughly every 10 minutes.

D&D is kind of rife with these sort of gems for creative use, and for me it is one of the charms it has over more rigid and literal systems. If you play a game where most of the powers and abilities are intentionally designed to be a toolkit for solving problems, squashing creative applications without strong game balance reasons will probably lead you down a path of putting out endless fires and you might be better off looking at different systems.

One thing I think we can all agree on, however, is that Skywrite should not be used to ask for nudes.