The Ritual move gives you all you ask for already!
Have the player tell you what they would like to achieve: gaining the ability to breathe fire permanently or temporary, or enchanting an item to grant them the ability to breathe fire, or whatever.
If the players' indications are not clear enough, ask questions and use the answers!
Then, with your players desires, look at the options that the Ritual move gives you and decide which of them are appropriate and fit your fiction as well as what the player wants.
Example: if they want to gain a permanent breath of fire, I would not reccommend a limited version by time. So the bullet points appropriate to the power level might be:
It takes a long time to learn, maybe a full decade or so.
You need the help of an ancient dragon to teach you his magic.
(First) you need to live with the fire, maybe in a volcano or so.
If you want to be less restrictive on requirements, or they ask you for an easier to accomplish version you could lessen them by introducing side effects or a lesser version: maybe they always breathe fire, or the flame will only be anough to light paper afire, maybe burn flesh but not really melt steel.
Mind Your Follow-Through
Note that Defy Danger starts out with:
When you act despite an imminent threat or suffer a calamity
Getting rushed by screaming kobold fanatics who've set themselves on lightning* is pretty calamitous, and if you hit on a 10+, that's great! But what it means is that the threat doesn't come to bear right now, not that it vanishes forever - "defy" doesn't mean "eliminate".
Yes, you are encouraged to start setting up the scene with softer moves, but all of these moves are things that are actually happening in the fiction. The players aren't trying to, like, counter and eliminate your moves or anything, they're also taking actions in the fiction and accomplishing their own things. They can manage to be both momentarily safe and still very much in danger.
So, you hit on a 10+. The screaming kobold fanatics haven't gone away. It's just that when the first one rushes into the innocuous-looking jar/carefully positioned Leyden mine and they both go up in a cloud of electroclasm and smoke, you're not right there with them.
Awful lot of jars in here, aren't there?
* no one ever said the path of the blue dragon fanatic would be easy
Mind Your Setup
Tell them the requirements or consequences and then ask is often underestimated, but it's an excellent way to extend the results of moves without having to write entirely new ones.
So if, for example, Stringfellow surveys the upcoming holosparkst, decides it's time for the better part of valor, and says he's diving out the nearest doorway, that does sound like Defy Danger too, doesn't it? But you can always say:
Sure, but things in here are ramping up rapidly. If you make it out, getting back in to help everyone else won't be nearly as easy.
Or:
Sure, but whatever that just kicked off is already cascading around the exits. You'll be taking 1d6 damage through armor just to try.
Or even:
Sure, but, gosh, there's all this smoke in here and your ears are still ringing from the blast. You can get out somewhere safely, but it's not entirely clear to you where that's going to be.
And then end with:
Is that alright?
And if it's not, then Stringfellow isn't going to dive out the door in the first place. His turn in the spotlight will be spent doing something else. And if it is, then even a 10+ on a Defy Danger will still leave Stringfellow in a bad position. It doesn't violate the spirit of the move to do this - accepting those known bad outcomes is just the cost of making the move in the first place.
Mind Your Prep
And, of course, if you knew all along that there'd be kobolds in these ruins and they laid traps like the dickens, you can sit down and craft custom moves to deal with this and take Defy Danger off the table as an initial reaction. Something like:
When Lightning's Claw springs their ambush on you, say who was the most cautious among you and have them roll +WIS. On a 10+, they pick 1. On a 7-9, the GM also picks 1. On a 6-, all 3:
- You're right where they want you. Everyone takes -1 ongoing to all rolls to dodge or escape, until you're out.
- You didn't see this coming. Pick someone else in the party to take the brunt of the first attack; the GM will make a move against them.
- They timed this one perfectly. All their damage is best of 2 rolls, and when they gang up it adds +2 damage instead of +1.
But you don't need to haul something like that out all the time, just for when you want it to be a sufficiently big deal that a regular Defy Danger doesn't seem like it should be able to resolve things satisfyingly on its own.
Best Answer
Let's have another look at the Know-It-All move (emphasis mine).
Now let's look at your proposed scenario: the Fighter is under attack and you've asked him the all-important question "What do you do?". In this scenario there are plenty of barriers to the Fighter getting his +1 forward and the Wizard gaining his experience. They could be overcome if the fiction allows it but would take some doing.
All in all, what you should remember is that Dungeon World is always Fiction-First. Your players don't tell you what moves they're using, they tell you what their characters are doing. If their fictional actions trigger a move then you as the GM let them know that they're about to trigger a move and ask if that's what they want to do.