Using Spout Lore to reveal a detailed, pre-created world is contrary to the rules.
There is a caveat I should make here. I'm going to talk about rules the GM has to follow. You're welcome to not consider them binding rules, but DW as designed does. If you don't follow the GM rules, you're "voiding the warranty" on the game and it will not operate as advertised. You're on your own then. (Incidentally, this is a close paraphrase of the designers [on p. 159 and in various conversations] – it's not just me saying so.)
For reference, these are the GM's responsibilities:
- Describe the situation
- Follow the rules
- Make moves
- Exploit your prep
… plus following the Agenda and Principles.
So part of your job is to "exploit" your prep, as in mining it and twisting it for the benefit of the current game session. You also have to follow the rules, which includes your agenda. And your agenda is (p. 161):
Your agenda makes up the things you aim to do at all times while GMing a game of Dungeon World:
- Portray a fantastic world
- Fill the characters’ lives with adventure
- Play to find out what happens
Note that doesn't say create a fantastic world – "portray" is a very deliberate word choice, as we can see by continuing the same quote (emphasis mine)…
Everything you say and do at the table (and away from the table, too) exists to accomplish these three goals and no others. Things that aren’t on this list aren’t your goals. You’re not trying to beat the players or test their ability to solve complex traps. You’re not here to give the players a chance to explore your finely crafted setting. You’re not trying to kill the players (though monsters might be). You’re most certainly not here to tell everyone a planned-out story.
So that's the trouble you're having: Spout Lore does let you, the GM, reveal a detail, but Dungeon World itself doesn't permit you to have revealing a big pile of pre-crafted details to be part of your agenda. Spout Lore isn't a opportunity to infodump on your players. In fact, it encourages the opposite with the agenda "Play to find out what happens." That includes about your world.
So why does Spout Lore not work well with pre-crafted worlds? Because in many subtle ways, the answers that players get won't be as interesting to them. The setting detail revealed existed before the PC did, so it's only maybe relevant or interesting to them and their adventures. (Note that Spout Lore requires the GM to say something interesting about the subject.) You are quite understandably going to be way more excited by pre-created setting details you reveal than the players are. If the Spouted information isn't as interesting as it could be, their motivation to use the move decreases. If it decreases below a certain threshold, they'll start seeing it as a "dead" move – one not worth taking when the risk is getting a miss. Other moves become much better value propositions for the same amount of risk.
Something created on the spot or quickly adapted to current circumstances and the flow of the game will be much more relevant and interesting to the players and their characters. By holding your world lightly in your mind and being willing to kill your darlings, you are serving the GM's agenda better. You're serving your players better, too. You can more easily come up with details that are pertinent, and more easily adapt the loose details you do have in your prep to your players' current game input, and as a result come up with something that's way better because it's leveraging the collaborative-narrative design of Dungeon World.
New answer for a renewed question. The old one is here
I'd say that a hidden move is quite against the grain of *World games'idea of moves. It robs the players of their agency in determining their characters' story.
And in your case, the intra-party conflict that may occur if the infiltrator is exposed seems to be more important than whether the infiltrator will be able to commit acts of sabotage and betrayal behind their backs. I'd base the move on that and add another move for the other party members to respond.
Infiltrator
You are an agent of your deity with a secret agenda. When you commit acts of sabotage and betrayal behind your comrades' backs, mark experience, and choose one comrade that doesn't already have it to receive the "Suspicious" move immediately.
Suspicious
You are suspicious of the infiltrator's weird behavior. When the Infiltrator commits acts of sabotage and betrayal behind your back, roll+INT.
- On a 10+, you have seen enough, but just need some more evidence. Replace this move with "Deeply Suspicious"
- On a 7-9, you noticed something unusual. Take +1 forward to your next "Suspicious" roll, but getting there wasn't easy. Choose one:
- You had to get into trouble to get your information and come back with 1d8 damage.
- Information is pricey. You had to spend 2d6x20 coin to find some clues.
- Lies are everywhere. You wrongly implicate another comrade (The infiltrator will tell you who). You cannot aid or interfere with them until the next time you roll "suspicious"
Deeply suspicious
Replaces Suspicious
Same as "Suspicious" but add these to the list of possible outcomes.
- On a 12+ , you have enough evidence to expose and implicate the Infiltrator. Now everyone in the party knows better. You decide the fate of the traitor.
- On a 10-11, you collect a solid piece of evidence, slowly building a strong case. Give another comrade the "Suspicious" move if they don't already have it, or replace their "Suspicious" with "Deeply suspicious"
This is based on the assumption that the infiltrator is a well known and trusted member of the party in the beginning. The first act of the infiltrator is essentially free. His or her comrades suspect nothing in the beginning and they trust the infiltrator. But then it gets harder and riskier every time.
And yes, all this can and will eventually leave the fate of the infiltrator in the hands of another player. The question is, when?
Best Answer
In practice, you stick to the moves and use the list, until you internalize it and no longer need to refer to the list, but even them you continue to use it. Just like when playing a Eurogame with a board, you do what the game says, exactly, if you want it to function as advertised.
The GM's moves are multi-purpose. They:
The list is super-important, because Dungeon World is not your average dungeon crawling RPG, and not using the list of moves usually results in running it as if it's some other game, and then wondering why it's not as great as everyone keeps saying.
In practice, what goes through my mind is either