I'm not sure if this has been brought up before or not. Teleportation usually becomes the party's main method of transporation once they get access to it, and once that happens its just a matter of time before the mage crit fails his check. What happens then usually falls somewhere between the rules and the GM; either the party is teleported thousands of feet in the air (and being high level, will most likey survive by being able to fly, teleport again, or take 20d6 damage), or the teleport into solid rock and are instantly killed.
But what if a critical failure in teleportation moved the subjects not through space, but through time. Instead of the party teleporting from their homes to the dungeon, or the next city over, they are thrown back thousands or perhaps millions of years to an age of great thunder lizards and serpents kingdoms. Or, maybe thrown ahead eons, when the world is a great, dystopic urban wasteland. It could be used as a jumping off point for another campaign, in which the party must change the future or undo changes to the past, or it could be used as a two session stopover while the party figures out how to get back to their own time.
If the pc's are trying to stop an bad guy in the present, teleporting them to a future where they weren't around to oppose him and he ended up ruling and/or destroying the world could be a good way to get home the message how important their mission is. Even if they just blip forward 10 years or so, they could meet all the people they cared about who are now broken and wounded (those that are lucky enough to still be alive) under the dominion of said villain, because the heroes weren't there to oppose him
But what if a critical failure in teleportation moved the subjects not through space, but through time. Instead of the party teleporting from their homes to the dungeon, or the next city over, they are thrown back thousands or perhaps millions of years to an age of great thunder lizards and serpents kingdoms. Or, maybe thrown ahead eons, when the world is a great, dystopic urban wasteland. It could be used as a jumping off point for another campaign, in which the party must change the future or undo changes to the past, or it could be used as a two session stopover while the party figures out how to get back to their own time.
If the pc's are trying to stop an bad guy in the present, teleporting them to a future where they weren't around to oppose him and he ended up ruling and/or destroying the world could be a good way to get home the message how important their mission is. Even if they just blip forward 10 years or so, they could meet all the people they cared about who are now broken and wounded (those that are lucky enough to still be alive) under the dominion of said villain, because the heroes weren't there to oppose him