In Pathfinder and Dungeons and Dragons, there is a spell called Knock, which opens any locked door, chest, whatever with a wave of the hand. Skilled Rogues can pick even magical locks. People can teleport, walk through walls, turn stone to mud, turn invisible, make themselves so strong that they can bend iron bars with ease, or control the prison guards minds. If you convict someone who has magical friends, or can cast spells themselves, how do you keep them imprisoned?

Let’s start with spells that can open locks. Simply don’t lock the door. Find another method to keep people in the room. Use a heavy door that can only be opened with a winch from the outside, like the castle portcullis. You could use a sliding door with a geared winch the same way. Or just put in a big rock and use multiple people to move it in and out of place. Bracing the door with weights, wedges, or posts can also work. These aren’t locks, so they won’t be affected.

Look at what is required for casting spells in your setting. Remove anything that could be a magical focus (wands, strange materials, and the like). In some settings, spellcasters need to have eight hours of continual rest to regain their spells. Simply wake them up every hour and make them exercise to deny that. Prevent them from meditating, communing, whatever they need to do in order to get those spells. Guards should be trained as to protocols for preventing spellcasting and should use them as if their lives depended on it because their lives depend on it.

Now that we have the most obvious things out of the way, we need to get up to speed on other ways prisoners can escape or be rescued and deal with them. Typically, this should be done on the basis of risk/reward. Knock is relatively common with no expensive components to cast. Therefore, the risk of escape using it is extremely high. The methods for preventing it are pretty inexpensive, so it’s pretty obvious that’s what we should do. The next most obvious threat is from teleportation. This is a much less common threat, as it’s a much more powerful spell. It is also pretty difficult to defend against. However, some of the strategies I discussed in my post on architecture in a magical world would also work with that. So, high value or high risk prisoners could be blindfolded, carried (to keep the distances secret), and put into a dungeon maze construction to prevent them from teleporting out or someone else teleporting in.

Finally, you can take a book out of some of our modern inventions and use a variation on the theme. For example, if your world features a spell that can turn stone into mud, perhaps your walls have a sheet of iron embedded in them to prevent that being useful. Too expensive? How about a wall of mortared rock, then a wall of logs treated to resist flame (something they actually did during medieval times). We use composite building all the time. I’d bet most of your house uses a wooden frame and dry wall. This is no different.

For powerful spellcasters, you might have a single cell that has walls made of special coatings, runes that activate to dispel any magic in the cell as it’s cast, or any number of defenses to prevent their escape. After all, how many powerful spellcasters are you expecting to commit crimes and be captured and held this way?

For my Blake Heira series, my jails and prisons offer several magical defenses. The Hall of Trials is laced with runes that protect the structure from scrying, teleportation, and magical attack. If someone casts any magic in most of the building, they will regret it. Because of various spells and effects, there are no bars on the windows. Instead, they use translucent quartz set in the walls to allow light in, but nothing else. In the prisons, they have constructed magic free zones to keep known spellcasters. They have a diviner come and check them periodically to make sure there’s no magic for them to use.

So, when you’re working on your setting, think about how frequently a spell could be used to get someone out of jail. The more common (i.e. the lower level) the spell, the more likely it is that they will have some sort of counter to it. It doesn’t have to be expensive, or even particularly complicated, but it should be something realistic.

Next week, I’ll be talking about how magic affects religion. Thanks for reading! I’ll see you next Sunday.