This is a power you should be very hesitant to give out to players. Be careful and do not do it lightly. Ideas borrowed from 5E.
Instant Transmission between points is considered one of the greatest achievements a Magi can ever obtain, along with achieving immortality and turning lead into gold. However, as the latter two are often considered morally or politically dubious, the first is the one primarily researched.
Almost all cultures have stories of how in ancient times, Magi or even normal people could instantly travel across the world with no more effort than crossing a busy street. However, depending on a culture's records, feelings about magic and potential losses of knowledge over time, whether due to political purges, wars or the slow erosion of time and entropy, this knowledge is often lost. If it is not lost, it is usually tightly controlled and often kept secret by either the most ancient and powerful Wizarding Orders or by a Cabal of State-sponsored Wizards: this may in fact describe the same group.
In other cases, the spell may be lost and concealed in the depths of an ancient ruin, a long desolate tomb, the laboratory of an extremely preoccupied Lich who was around when the precursor civilization your race squats amid the detritus of or flying freely through a turbulent region of the Astral Sea.
In a more high-magic setting, Teleport is still a rare spell, but it isn't impossibly rare. It is, in fact, a highly dangerous tool of espionage, assassination and state-craft. Any nation that has access to Teleport will be able to dominate those of it's enemies that do not. You will find agreeing to a treaty or military alliance much more convincing when you know that there is a risk that your rivals could teleport a pack of armed killers into your Sovereign's bedchamber.
R: touch T: objects D: 0
Up to [sum] touched objects and/or creatures are teleported to a location of your choice. When casting this spell, roll 1d20 on the 'Teleportation Result' table and modify it based on the destination you choose and your method of targeting the location.
1-5: Mishap. Your journey is not smooth- all creatures and objects transported take 2[dice] damage. Additionally, 1d4 [1= A stranger appears at your destination with you. Roll on the 'Man out of Time' sub-Table; 2= You arrive 1d20 hours after you left, though you did not experience this time lag, to you it happened in an instant; 3= You are blasted with extra-universal radiation, you take 2d6 CON damage, save for half. CON is restored at a point of 1 point per day. If reduced to 0 CON, a creature dies; 4= You are exposed to alien geometries and cosmic knowledge- save or develop an insanity. Roll on the Referee's favorite insanity table or roll on the 'Cosmic Madness' sub-Table below.]
6-10: Similar Area. You are transported to a similar area to the one you targeted. For example, if you wanted to go to a your Wizard's Tower, you will end up in a Wizard Tower, but it could be one anywhere on the same plane of existence. If you wanted to teleport to a King's Palace, you might end up in the Palace of a foreign monarch on the other side of the world.
11-15: Off Target. The DM should roll 1d10*1d10%. The first d10 determines the direction you traveled and the second d10 determines the distance you are off target. The directions for the first d10 are [1= North; 2= Northeast; 3= East; 4= Southeast; 5= South; 6= Southwest; 7= West; 8= Northwest; 9= Upwards; 10= Downwards.] So, for example, if you tried to travel somewhere that would take 30 days to travel to and rolled 'Off Target' then got a "5" on the first d10 and a "3" on the second, that means you end up 9 days South of your intended destination.
16-20: On Target. You arrive at your intended destination.
- Permanent Circle (+15)
- Associated Object (+10)
- Very Familiar Location (+5)
- Seen Casually (+3)
- Viewed Once (+2)
- Description (+1)
- False Destination (-5)
- Rolled Chaos (-5)
- Rolled Corruption (-10)
Man Out of Time:
1- The stranger is from a different era of your world. He* is from 1d6 [1= The distant past; 2= The recent past; 3-4= The present; 5= the near future; 6= The distant future.]
2- The stranger is from a different plane of existence. He is from 1d3 [1= One of the Accursed Planes; 2= One of the Parallel Worlds; 3= One of the Blessed Planes.]
3- The stranger is random copy of one living creature that was transported.
4- The stranger is an Outsider, a Spirit, Angel or Demon that was accidentally snagged by the caster's spell and inadvertantly dragged to this location.
*Obviously the stranger could be woman/female.
1- "The Stars, they See!" You become convinced the stars are watching, observing and judging you. You must avoid them as much as possible. Camping outside without a tent or something to cover yourself is impossible- being outside at night is difficult, any thing that means they might see you is painful.
2- "Life is just one sick, demented gag." The World is absurd, you realize. You have a hard time taking anything seriously, as nothing means anything.
3- "I am God made flesh." You realize you are in fact, a God, a divine immortal stuffed into this frail, temporary vessel. You may seek suicide, worldly immortality or apatheosis, but you cannot remain as you are.
4- "The End is Nigh." The World is going to end, and soon, you realize. You must prepare.
5- "I am a Laughing, Walking Mockery." You realize that you have utterly failed to live up to your potential/destiny and thus develop the most crippling case of imposter syndrome imaginable.
6- "The Weave of Fate is Iron Thread." You realize your own destiny is absolute- it will happen, no matter what you wish to occur. You develop a staggering fatalism and an apathy to match.
Terms to Know:
Permanent Circle: These are circles or locations inscribed with a unique series of arcane runes. If memorized or studied before casting the spell, a Magi can 'lock on' to these runes, allowing the Magi to arrive at the destination with relatively little risk. These Circles are often located within ruins or in the relics of older, more advanced civilizations. If more contemporary cultures have built any, they are usually kept secret and under heavy guard to prevent enemy Magi from being able to use them to bypass other defenses.
Associated Object: This is an object associated with the location you want to go to. For example, a stone from the Archmagi's garden. Using this, you can teleport to the garden of the Archmagi with relative ease. Note that Associated Objects only last 6 months or so, and must be regularly refreshed. They also only take you to the same space as where they came from. You can't use a stone from the Archmagi's garden to teleport into his parlour.
Familiarity: How well do you know the location? Very Familiar means you have been there multiple times and have a good sense of the location, Seen Casually means you have been there once, while Viewed Once means you have only seen the location once, either from a distance or through some other means, such as a Scry-glass.
Description: You have heard a description of a place or read about one in a book. If the description you used is false or very inaccurate, this counts instead as 'False Destination'.
False Destination: You attempted to teleport to a place that doesn't exist or is very different then you thought. For example, if you tried to teleport to Atlantis but did not know it had been sunk beneath the waves. Regardless of what result you roll on the Teleportation Result table, to determine your actual destination, the Referee should select a 'Similar Area' that most resembles what the spell-caster had in mind.
How do I stop this?
Tetragrammatic Runes are symbols that when formed in the physical world, influence the effect of magic. Some attract magic, while others repel it. Tetragrammatic Runes are not magical themselves, but can produce similar effects when laid out in proper patterns. One pattern, also called Gate Wards, prevent teleportation or the opening of portals within the warded area. These wards are often carved into stones at the edges of important buildings, engraved into metal sheets which are placed against the walls or carved into wood or metal decorations around important rooms. These protections are considered as paramount for the protection of vital assets and important personnel, such as the Sovereign and his/her family, important military leaders and etc. Even in cultures where knowledge of these wards has been lost, the Ward-signs themselves often stick around as symbols of protection or good luck.
1- A group of Magi want to harm a rival. They hire you to break into one of the rival's secure buildings and find the teleportation circle hidden inside. Record the runic sequence on the circle and return without giving away your intentions. If they discover you were after the runic sequence, they may destroy the circle and thus no one will be able to use it.
2- A group of Magi want to harm a rival. Convince them that you are a traitor to your employer's cause and give them misinformation, including this false runic sequence. When they try to use it, it will only harm their rivals.
3- A group of Magi want to harm a rival. Go to the location of their enemies and secret inscribe a runic sequence to allow the Magi to teleport something there. You'll also need to trash any Wards against teleportation you find there.
4- A powerful Magi wants to go to a location that is dangerous or inconvenient, but doesn't want to take the risks. Go to the location and bring him back an item that will allow him to teleport there safely.
5- An artistic savant has been discovered who is able to flawlessly recreate things he has seen in highly detailed sketches. He would be a great asset to our Magi and a threat to us, should our enemies manage to get their hands on him. Find a way to recruit him to our cause or dispose of him, if the former option is impossible.
6- A Teleportation attempt gone awry has led to a stranger who claims to be from the far future to appear in the present day. The stranger also says that a catastrophe that he recalls from history has not occurred yet. Find out if what this stranger says is going to happen is true.
7- A Magi tried to teleport and instead never arrived. A powerful Demon reached out to your employer and told him that the Demon knows where the Magi is and will exchange the information for something important, valuable or dangerous. You have been hired to either bring the Demon what it wants, try to prevent the Demon from betraying your employer, double-cross the Demon first or some combination of the following.
8- The party teleported and ended up in the past. If they change things too much, maybe they'll be erased from history, Marty McFly-style. Or maybe they need to help something occur, Prisoner of Azkban-style. Either way, the overseers of Time are pissed off at this intrusion and are hunting the players. You don't want them to catch you, as you'll end up in Time Prison, or worse.