In a discussion about high level play in several games recently, it came up that a lot of games - and GMs - create challenge for their events not by confronting the players at the level they're supposed to be, but by negating options that the players can use so the challenge has to be faced a certain way. This feels like a knee-jerk reaction to the idea that the PCs can become "too powerful." I strongly disagree with that being a thing, but even if I acknowledge that the PCs can become too powerful...that is no reason to punish the players. After all, the only way the PCs become too powerful is if the GM gives them that power.
Today though, I want to talk about why you don't want to just say certain abilities can't be used and explore the symptoms and thoughts that lead to that conclusion.
Caveat: High Level Challenges Have High Level Abilities
Before we begin, I want to explain that I'm not against all forms of negation of PC abilities. It makes sense that a high level enemy designed to challenge the PCs has the ability to counter or negate certain abilities. For example, it makes sense that a powerful wizard has a home warded against teleportation and divination magic. It also makes sense that you can't solve the problem of the Imperial Chancellor in Rokugan by challenging them to a duel without first doing all the necessary setup for them to not just laugh you off.
But there is also a difference between the Arch Mage Ragnos having a home you can't teleport into or divine into as a feature of the world, or as part of a trap, and the PCs just randomly not being able to teleport out of a spot of trouble they got into. There is also a difference between Ragnos having this defense, and every opponent the PCs come across once they cross a certain threshold having that defense.
One is a challenge. The other is just curtailing solutions because you can't find another way to challenge your players.
The Problem With Negation
The problem with negation is one of feel. The reward for hitting high levels of power is the ability to do those cool things. When you deny the PCs the use of those abilities, you deny them the reward for playing their character. It would be like if you couldn't spend your money after working for it. Technically it is there, but it is useless because it is never allowed to work. Let your players use those abilities. Let them feel like badasses. Trust me, you'll find ways to challenge them.
The Core Problem: High Power Abilities Negate Key Parts Of The Game
This is very obvious in D&D 5e but holds true in other games as well. The more powerful the PC, the less of the game they have to deal with. An L5R character with high social position can ignore the consequences of being rude most of the time because they have so much social position no one will question it. A high level wizard with the Magnificent Mansion spell never has to worry about a safe place to sleep - or food, or access to research libraries.
Games get to a point where the PCs can just brute force through things. You put a bunch of level 3 characters into Ravenloft and the game is a high danger survival horror with death lurking in every shadow. You drop a party of level 16 adventurers into Ravenloft and it's just kind of a joke. When the fighter can solo Strahd without burning an Action Surge or Second Wind in one round it's hard for much else to stack up.
Money Is Power Too
Power isn't just abilities by the way. Money is power. You see lots of people looking for advice on how to deal with their players getting tons of money, and the most common response is "take it away." This is basically the same thing, and we're addressing that too.
Motivation and Consequences
When you boil it down Motivation and Consequences are at the heart of all these games, and by focusing on them we can solve the problem. So what is the problem? I mentioned it above. So how do we make a character capable of negating an aspect of the game not do that? Simple, we give them motivation to do so and with that motivation make them aware of the consequences of negation.
For example, in my D&D game I have PCs capable of such feats of travel that random encounters are just a thing of the past at this point. It is honestly a relief for me because I'm not a huge fan of random encounters, but it is part of running D&D. So how do I make my PCs deal with random encounters? Simple, provide motivation. In a recent adventure the PCs were asked by a desperate mother to find her missing son. The son went missing traveling between two key points in a large area of land. The PCs want to help this woman. Now they can just skip to the next place and check there, but in doing so they miss risking the son in the area between. And missing the son could increase the chance of him being dead. They now have motivation to travel the distance more normally while looking for the son. Which in turn means they're on the road, and thus open to random encounters.
The same strategy applies for every problem. How do you stop your PCs from just teleporting away from all of life's problems? Motivate them to stay. How do you stop the Imperial Chancellor PC from just having his problems assassinated? Motivate him to face them through other means.
What Will They Do, Not What Can They Do
I mention this a lot, but if you focus your preparation and game around finding out what your players WILL do with their characters, instead of what they CAN do you will have an easier time. In a confrontation of "CAN do" the GM can always win. Worst case scenario just clone the PCs' stats, double them, and use their own tactics against them. It's easy and gets old (for me) fast.
But when you focus on what they WILL do, you can get all sorts of interesting reactions. And once you know what the PCs value, you can threaten it to see what choices they make.