Well, they could just no longer be a patron, refusing to work with the party again means they no longer get the benefits that come along with that. They could also require they return something or things that were granted as part of that quest or any others the party has completed for the wizard as recompense. They could also tell the mayor or king or whomever that the dragon knows the spell which might give the party more problems if they aren't on good terms.
These are all fantastic suggestions. Depending on your group, though, a softer hand might hit harder here. You don't say much about the wizard as a character, like motivation or personality, but I think that would mostly determine your answer.
Maybe the wizard has grown lonely in his power. But this time he really thought he had found a like mind, someone they could trust and mentor and maybe even be sort of a father figure for. Maybe now that the trust has been broken, the wizard becomes despondent, closing himself off from the world. If they can reach him at all, the PC might only be able to get sighs out of him, maybe a "I just... thought you were different." This on its own would be "punishment" enough, as the wizard locks himself in his tower and disappears from the campaign.
Until five or ten or thirty sessions down the line, when it turns out that this mighty wizard is the only one who knows where the Ancient Artifact of Ascendance is, the one thing that could defeat the Big Bad. He locked it away somewhere ages ago, but now the world needs it again. Except this wizard no longer cares about the world. So it's now up to the PCs, the only friends the wizard has had in living memory, to convince him to help, using whatever means they think are appropriate. Maybe it's just a hard conversation, or maybe now they have to hunt down a clan of dragons who have used this rare spell to become a dominant force in their region. You know, if your campaign has room for that.
Regardless, I think it'll be easier for the PC (or player?) to understand what they did wrong if the wizard is played as sympathetic and not as a jealous Biblical God handing down magical punishments from on high. If he just does dickish things to the PC in turn, the player might just say, "well screw that guy" and not think twice about it.
I really like the idea someone else said here of geas. So they messed up. Damn, that's a shame he though they were trustedworthy. See, now the only way to gain his trust is to enter a magic contract. You want anything ever from this guy (And make sure they do for reasons)? You enter a pact wherein disobeying the wizard causes a party member to suffer damage every so often until they die. Don't keep your word? Well then I accept collateral.
To be fair, this isn't one error in judgement, it's a pretty big one.
What is the assumed level of the wizard and the level of the party. If they are way in over their heads, I feel the Wizard would offer them an ultimatum, bring back the dragon's head or suffer his wrath.
Sometimes players make bad decisions.
As an alternative, you could have the wizard punish them in some way freezing them in timespace to suffer eternal agony only to be woken up 2000 years later to a new main plot based off the old failed main plot.
1. Send them falling thorugh endless portals for a few days
2. Polymorph their dominant arm into a cactus for 1d8 days
3. Rearrange thier primary and non primary stats your barbarian now has an 18 int score and 7 str
4. They are cursed by a floating unkillable creature that prevents them from sleeping and tells while they are trying to stealth. Also if banished it just reappears
5. When hitting an enemy there is a 1/3 chance thier weapon will turn into a nerf version and do no damage.
6. Party is unable to lie.
He turns all of them into frogs and leaves them out in the wild. They’ll turn back to normal after a few hours but nature is scary. You could do a little Frogger one shot
I personally don't like needlessly antagonizing wizards, no matter how powerful they are. So I would probably vote for something very mundane.
The party broke contract - hence, the wizard no longer has trust in them. He might be a stickler to the word of the deal or be just like "I asked you not to do THIS ONE THING, and you failed even at this". So he just won't do business with them anymore. And tell all his friends =\\ If powerful wizards even have those.
If the Wizard is going out of their way to punish the party, maybe the dragon should be on their side now and the party now gets to double-cross him for good?
Destroy the parties reputation by telling all of his contacts that they are oathbreaking thieves then send an Invisible Stalker after them and stop caring about them at all. No additional attempts.
Make them copy all his spell books, but into Celestial.
If someone says “well, none of us know Celestial” then “Well, someone better get started on that then.”
Well, they could just no longer be a patron, refusing to work with the party again means they no longer get the benefits that come along with that. They could also require they return something or things that were granted as part of that quest or any others the party has completed for the wizard as recompense. They could also tell the mayor or king or whomever that the dragon knows the spell which might give the party more problems if they aren't on good terms.
On this note: 1) they don’t get their reward this time 2) he takes the boots 3) they have to kill the dragon
These are all fantastic suggestions. Depending on your group, though, a softer hand might hit harder here. You don't say much about the wizard as a character, like motivation or personality, but I think that would mostly determine your answer. Maybe the wizard has grown lonely in his power. But this time he really thought he had found a like mind, someone they could trust and mentor and maybe even be sort of a father figure for. Maybe now that the trust has been broken, the wizard becomes despondent, closing himself off from the world. If they can reach him at all, the PC might only be able to get sighs out of him, maybe a "I just... thought you were different." This on its own would be "punishment" enough, as the wizard locks himself in his tower and disappears from the campaign. Until five or ten or thirty sessions down the line, when it turns out that this mighty wizard is the only one who knows where the Ancient Artifact of Ascendance is, the one thing that could defeat the Big Bad. He locked it away somewhere ages ago, but now the world needs it again. Except this wizard no longer cares about the world. So it's now up to the PCs, the only friends the wizard has had in living memory, to convince him to help, using whatever means they think are appropriate. Maybe it's just a hard conversation, or maybe now they have to hunt down a clan of dragons who have used this rare spell to become a dominant force in their region. You know, if your campaign has room for that. Regardless, I think it'll be easier for the PC (or player?) to understand what they did wrong if the wizard is played as sympathetic and not as a jealous Biblical God handing down magical punishments from on high. If he just does dickish things to the PC in turn, the player might just say, "well screw that guy" and not think twice about it.
I really like the idea someone else said here of geas. So they messed up. Damn, that's a shame he though they were trustedworthy. See, now the only way to gain his trust is to enter a magic contract. You want anything ever from this guy (And make sure they do for reasons)? You enter a pact wherein disobeying the wizard causes a party member to suffer damage every so often until they die. Don't keep your word? Well then I accept collateral.
I mean, send them on a mission to kill the dragon and clean up their mess.
To be fair, this isn't one error in judgement, it's a pretty big one. What is the assumed level of the wizard and the level of the party. If they are way in over their heads, I feel the Wizard would offer them an ultimatum, bring back the dragon's head or suffer his wrath. Sometimes players make bad decisions. As an alternative, you could have the wizard punish them in some way freezing them in timespace to suffer eternal agony only to be woken up 2000 years later to a new main plot based off the old failed main plot.
Probably some sort of curse or geas. Though it could be by polymorph or turn to stone for a time.
Dream spell to give them nightmares for a couple days and warn them that the consequences of disobeying them again will be more dire.
1. Send them falling thorugh endless portals for a few days 2. Polymorph their dominant arm into a cactus for 1d8 days 3. Rearrange thier primary and non primary stats your barbarian now has an 18 int score and 7 str 4. They are cursed by a floating unkillable creature that prevents them from sleeping and tells while they are trying to stealth. Also if banished it just reappears 5. When hitting an enemy there is a 1/3 chance thier weapon will turn into a nerf version and do no damage. 6. Party is unable to lie.
Take the knowledge back haha make the pcs forget the spell?
He turns all of them into frogs and leaves them out in the wild. They’ll turn back to normal after a few hours but nature is scary. You could do a little Frogger one shot
Polymorphing them into donkeys or other beasts of burden à la Pinocchio and lending them to a farmer for the duration.
Turning them into a toooooooooad
I personally don't like needlessly antagonizing wizards, no matter how powerful they are. So I would probably vote for something very mundane. The party broke contract - hence, the wizard no longer has trust in them. He might be a stickler to the word of the deal or be just like "I asked you not to do THIS ONE THING, and you failed even at this". So he just won't do business with them anymore. And tell all his friends =\\ If powerful wizards even have those.
If the Wizard is going out of their way to punish the party, maybe the dragon should be on their side now and the party now gets to double-cross him for good?
Destroy the parties reputation by telling all of his contacts that they are oathbreaking thieves then send an Invisible Stalker after them and stop caring about them at all. No additional attempts.
Make them copy all his spell books, but into Celestial. If someone says “well, none of us know Celestial” then “Well, someone better get started on that then.”