Travel in the Middle Ages was full of dangers and uncertainty. On the other hand magical portals can make travel much quicker and safer.
Most of the post was written as the players I told you about before started toying with a portal in the Uplands, and I had to come up with destinations. Then I started working on it, then Albert from Underworld Kingdom/World of Ortix joined in, then we decided that maybe, just maybe, there’s enough to be written to fill a small booklet. So there you go, two of the worst procrastinators of the OSR (we are getting better though! Albert is actually finishing a lot of material nowadays and I’m, well, trust me) joined forces to bring you swag. So here you’ll see a really really brief treatment of the topic and a small excerpt of the final content.
Anyway, bridges and fords might be washed away, roads might be blocked by fallen trees or brigands[*], forcing travelers to take long detours. Portals on the other hand warp space and time, pin it on a physical aperture due to sympathetic magic principles while negating the illusion of distance between two places and allowing to step through the stabilized warp. Or something equally silly.
My formative experience with portals was made under Waterdeep in a videogame called Eye of the Beholder, which lets you trample around what might or might not be a much much smaller (and actually completely unrelated) version of of the Undermountain until you die or you slay the titular monster. So, if you see something like this:

You only need to open it with the appropriate key to make it go all crazy like this (please ignore the different stone background):

And then open (again, different stone background):
Then you can have a stroll on these freaky stepping stones on the black abyss with not even a single little star and reach the other side, which can be very close or very very far away. YES, no brigands on the way, took only two hours, the slaughter of a goblin tribe and 2000gp to buy the key off a shady dude in town instead of three weeks on riding across the wilderness under the rain. I told you it would be convenient.
Anyway, there are three important concepts about portals: structure, destination and opening. The book will treat them more extensively, but you can have some small excerpts first.
Structure
The structure is how a portal appears. The portals in the pictures above look like number 1 in the table below. Roll 1d6.
- a wall with an ornate (gilded, carved etc.) basrelief or friese of a gate or door.
- a door. it looks like an ordinary door and works like a door. If properly opened it swings open on the destination.
- only a marked location. When opened a flight of stairs opens, leading down.
- a huge mouth with humongous fangs. Or maybe it’s a real mouth?
- a big stone/wooden/bone/crystal/metal/whatever arc.
- a well or pit in the ground, when opened filled with a rainbow mist.
Destination
The destination might be somewhere in your campaign 1d1000 miles away. Or 1d1000*1d1000 miles away. Or some other random place. Either decide or roll 1d10 on the table below.
- an hidden treasure room. Unfortunately, the magical passage closes after passing through it and probably there’s no other way to exit the room, maybe except some hidden passages or thin walls.
- a tower in a city made of brass, surrounded by a sea of flames.
- a beach of an island in the Aegean sea. There is a sheep pen close by, vineyards and olive trees. You can see a cave in the cliffside as well, with 1d6 hungry cyclops (LVL 13 giants) living inside.
- underwater, 100 yards away from a castle made of red coral, 3d6*10 mer-people lead by the King of the Waves (LVL 4+1d6 multiclass fighter/cleric/mage)
- the private quarters of a lich.
- the realm of a demon prince
- a desolate and forgotten mountain stronghold
- a dragon’s lair (there’s 75% chance that a dragon is present, guarding the treasure)
- an ancient graveyard or subterranean tomb complex
- a dungeon, level 1d10.
Opening
To open a portal you need a key. As Planescape and myths teach us, keys can be whatever. It’s usually somehow related to the circumstances of the portal-building. Roll on all the following tables first, then join the dots and feel free to ignore those that don’t fit your game:
the key is… (roll 1d6)
- a physical object, touching the portal. 2-in-6 of needing a specific object, for example the sword of the High King. Examples: roll 1d6:
- a key
- a jewel
- a stone
- a weapon
- water
- a stone
- something physical, but with metaphysical connections, touching the portal. Examples: roll 1d6:
- blood of a sorcerer
- blood, sweat and tears of the builder
- dragon breath (bottled is fine too)
- ectoplasm
- mana tar
- holy water
- an emotion or feeling, truly felt within close distance. Examples: roll 1d6:
- anger
- lust
- hunger
- despair
- terror
- pining
- a specific time. Examples: roll 1d6:
- twilight
- a specific time of the day
- when the stars are right (a specific moment of the year, like an equinox, solstice or 4:30AM 12 days before the last day of autumn)
- some astronomical alignment or opposition
- an eclipse
- 1d100 hours/days/weeks/months/years after it opened last time, reroll every time
- a sacrifice, right under the portal. Examples: roll 1d6:
- a burnt offering of food
- an animal slain, blood sprayed on the portal
- a weapon blade must be broken
- a gem must be shattered
- fasting for 1d6 days
- mutilation of a small but significant body appendage, roll a d6:
- ear
- eye
- nose
- tongue
- a finger
- any will do, like hair, a wart or nails
- an action must be carried out in front of the portal. Roll 1d6:
- a specific magic glyph must be traced on the portal
- 1d6+1 people must have a specific kind of steamy hot kinky ritual sex around the portal
- a specific magical/mystical ritual must be celebrated in front of the portal to open it
- the password must be (1d4)
- shouted
- spoken
- sung
- traced on the portal
- a prayer must be (1d3)
- sung
- spoken
- silently recited
- a spell must be cast. Roll 1d6:
- a unique spell designed specifically to open this portal
- Knock or equivalent
- an elemental-based spell cast on the portal, element depending on the “related to” result
- any demonic/necromancy spell
- any clerical or theurgic spell
- any spell but it must be cast directly on portal (like trying to heal it)
- an event, happening somewhere relatively close to the portal (a few hundred miles, or in the same part of the continent). Roll 1d6:
- the death of the king of the land or something equally pretentious
- a cockatrice hatches from a cock’s egg
- the last copy of a spell is burnt
- the first lightning from a nearby summer storm
- a star falls
- famine strikes the land
- two keys are needed to open the portal, either both keys at the same end or one at each end. Roll twice on this table. Reroll results if for some reason make the portal impossible to open. If rolled more than once, keep on adding keys.
- This portal can be used with different keys (2d6). 2-in-6 chance of different keys leading to different locations.
- Some part of the portal that is currently missing. It may be a part of the sculpture, a missing gem in the portal’s decoration or something similar. If you want to be fancy and love in-jokes, the key is the keystone of the arch (or equivalent) which at the moment is collapsed on the ground.
and it’s related to… (roll 1d6)
- one of the two sides, 50% chance each. 2-in-6: the link is one way only toward the relevant side. 2-in-6: the key can instead open d6-in-6 portals to the same side as well, but always one-way only and always toward the same end. Example: a wooden ring made from the tree that stood where one of the portals stands.
- both ends. Example: the portals’ architraves are made from the same stone block, the key is a small leather pouch containing the stone powder created when the architraves were sawn off.
- something else. Possibly something off-world that the PC will find, like magnetic cards. Whatever.
- well, there are two keys, each one-way only. Roll twice.
- and more. nothing specific, actually anything like that will do.