You could let the cleric use a less-optimal version of Bend Bars, Lift Gates as a custom move.  On a 10+, choose 2.  On a 7-9, choose 1.  (The fighter's move gets to choose 3 or 2.)

So on a 7-9 in your example, he probably picks "it doesn't take a very long time."  That means it does make a lot of noise, can't be fixed again, and damages something of value.  (You might have to get clever with the "something of value"; maybe ask the players.  At the very least, you could do damage to the cleric or give him the Weakened condition with a seized-up back.)


Regarding the barbarian's d8+d6: I haven't run one, but I'd make be all about escalation.

The d6 is higher on a hack n' slash roll?  He knocks over a brazier and starts shit on fire; smashes the orc into the pillar so hard it cracks and the ceiling starts to buckle; cleaves through the goblin and gets his sword stuck in the wall. 

D6 is higher on a parley?  Maybe you offend an onlooker with your impudence or rude manners.  Maybe you make a softer man envious and he starts to plot against you (nothing says that the GM has to introduce the complication now).

One last thought: don't think of it so much as the 7-9 result on Defy Danger.  There, the GM offers you a hard bargain, ugly choice, or worse result.  The barbarian shouldn't get any choice. He acts boldly and with vigor, and damn the consequences. 

Wow.  This looks really fun.  I really like the feel evoked by the different playbooks.  The sage is probably my favorite in that regard.

Any chance of seeing the new (v.04) basic moves, etc.?

Also, it's a conversation happening, right?  When the player spends that first hold to reach the gang leader: "cool, how do you do that?"  And after he describes it, you describe the reaction of all the people around him and the leader.  That's your opportunity to make a setup move, introduce something that the PC has to react to (imminently) or not like the consequences.  He might be face-to-face with the gang leader, but a half-dozen mooks are now staring down their barrels at him.  "What do you do?"

Sure, he can then spend his second hold to kill or disable the gang leader.  But once again, you say "sure, how do you do that?" and you've got the final say on whether he's killed or disabled and what that ends up looking like.  You're well within your rights to have the gang inflict its considerable harm right then. 

If he spends his third hold to avoid that harm, it's once again a "how do you do that?" with an bonus of "while you're disabling the gang leader?"  Even if he comes up with something, it doesn't extricate him from the situation he's in: behind enemy lines with lots of attention on him and no more magic miracle hold.  That's quite the spot.  Also, the hardholder's gang is about to attack?  What weapons are they using?  Guns and grenades and molotov cocktails?  Are they disciplined & skilled enough to avoid catching the touchstone in the crossfire?

I'm not saying Indomitable isn't wicked powerful, or that this wouldn't get old after a while.  But the player shouldn't be able to roll 10+ and go "I spend 1 hold to get close to the leader, another hold to kill or disable him, and my last hold to avoid the gang's harm."  "To do it, do it" applies to spending hold as much as any other move.  Spending hold changes the fiction, and the fiction responds and evolves.

The specific wording is:
"•You draw unwelcome attention or put yourself in a spot. The GM will tell you how."

"Unwelcome attention" is pretty loose and flexible.  It doesn't need to be "more monsters show up, fight now."  It could be
- an enemy/heretic of the cleric's deity senses their presence in the dungeon, and starts searching the halls/making preparations
- spirits of those who died previously in the dungeon are drawn to the cleric and ask him for succor, release, or closure
- intelligent mice might see the cleric's healing powers and claim that he must be the Chosen One their prophecies speak of
- an intelligent artifact in the dungeon might turn its magic eye on the PCs and start to arrange events to get into/stay out of their possession.
- a planar entity opposed to the cleric's deity might sense that deity's minion meddling in the affairs, and send its own entity to the dungeon's villains
- the deity itself might be the unwanted attention:  "REALLY, DURGA, *THIS ELF SWINE* IS WHAT YOU SPEND MY FAVORS ON?"

The unwanted attention doesn't need to escalate things right here and now if you don't want it to.
It could be It could be a perfect opportunity

Logistically speaking, I see these problems:

1) Discern Realities requires that the players know what questions they can ask.  On solution might be to have them ask 1 or 3 questions of their choosing, but you only answer questions from the Discern Realities list.  Like, they might ask "are there any tracks here?" and you answer the question "what isn't what it seems?", telling them that there aren't any tracks but it seems like someone swept the area recently, carefully covering their tracks.  Or someone asks "is she lying?" and you answer "what here is not what it seems to be?"  I think you'll sometimes give them answers they weren't quite looking for, but that's probably OK.

2) Spending hold from Defend is also tricky without knowing what their options are. Like, how do I make decisions about how "hard" to defend someone if I don't know how much hold I've got or I don't know the possible outcomes it can have?  

3) Many advanced class moves interact with the basic moves. As I advance a level, how do I know the value of Follow Me if I don't know how Perilous Journey works? How do I know when to use Blot out the Sun if I don't know when I'm triggering Volley?

I think these are surmountable, but they are real issues that should be addressed. Otherwise, you're taking away player agency.

I'd mostly handle it like Noofy said: stay focused on the fiction, asking specific players what they do and letting the moves flow naturally from they're responses.  Sprinkle that with a liberal amount of GM setup moves (telling requirements or consequences and asking, showing signs of approaching threats, showing downsides of class/race/gear, using monster/danger/location moves, etc.), and you've got a good chase scene. 

With that said, I find the wording of Defy Danger to sometimes leave me hanging on the 7-9 results.  Here are a couple custom moves that might be helpful & evocative in a chase scene:

When you race against time, roll +Int (if you're thinking quickly) or +Dex (if you're acting quickly). On a 10+, you make it with time to spare. On a 7-9, there's not a moment to lose. The GM will present a final obstacle, threat, or cost. Deal with it or let time run out.

When you pursue your quarry, describe how you do it and roll. If you do it...
...with agility and fleetness of foot, roll +Dex
...through dogged endurance, roll +Con
...by following the signs of their passage, roll +Wis
...by asking around after them, roll +Cha
On a 10+, you corner your prey or catch them in the open. On a 7-9, the GM picks one:
--You've almost got them, but there's an intervening obstacle or challenge
--They've gone to ground; you know where they are but it's a challenge to get to them
--They turn unexpectedly and attack

Note that neither of these "stop the NPC."  You might race against time to get to the doorway before the orcs can run through it, or to get within fighting range before they reach their giant allies.  But once you do that, you still have to say *how* you prevent the orcs from continuing to flee.  Stab them?  Shoot at them?  Tackle them?  Parley? 

If you think about chase scenes that *don't* involve one side getting away, they always end with some kind of confrontation or conflict. The chase just gets the pursuer close enough to force that confrontation.

I think the key is to determine who the PCs would be and who the NPCs/dangers/monsters would be.

I'd assume that the PCs are part of the Thorin's expedition, though you'd have to establish what they were in it for.  I think you might need to drop the larger "Sauron is returning" theme related to the One Ring and Mirkwood.  I'd also drop Gandalf (at the most, I'd make him a PC that was maybe 2-3 levels higher than the others).

Thorin himself and maybe some of the other dwarves on the expedition would probably be a danger.  Probably something new, like Rogue: Ambitious Hier.  Danger moves that involve rallying support, alienating allies, putting others at risk, acting irrationally.  Doom: Tyranny (lording over others in the region)

For other threats, just spitballing here...

If you use the movie, you've got the Pale Orc hunting Thorin (Horde: Wandering Barbarians).  Doom: destruction (of Thorin & his dwarven followers).

You've got the Misty Mountains & their Goblin King (Horde: Underground Dwellers). Doom: Impoverishment (company is plunged into slavery).

Mirkwood could easily be a Cursed Place (shadowland). Doom: Pestilence (as the darkness spreads into the realm of the elves and beyond).

The wood elves, probably an Ambitious Organization (Misguided Good). Doom: Usurpation (of the dwarve's ancestral home)?

Smaug is clearly an arcane enemy (dragon). Portents: ravens return to the mountain.  Some fool wakes the dragon.  Someone steals from the dragon.  The dragon attacks Lake Town.  The dragon lays waste to the entire region.  Doom: destruction. 

Biggest problem I see that is that many of the largest dangers in the story are just obstacles that need to be overcome.  The Goblin King and his people aren't going to do much more than sit in their hole and defend it, take prisoners, and eat them.  The only reason they're a problem is because the company passes through their territory and falls into their clutches.  So it's hard to come up with Grim Portents that aren't reactive to what the party does.  Same thing could be said about Mirkwood... it's just an obstacle to be traversed & overcome.  You'd have to give it more agency than is presented in the book to make it really become a Danger or a Front.

The key is that Thorin needs to be a problem almost as much as an ally, and thus a front.  And you need to have other parties capable of waking Smaug, possibly because of relatively widespread knowledge that he's been unseen for 60+ years and the telltale signs of birds returning to the mountain.  Then it's not just a delve into the dungeon with a dragon in it, but a race against time and possible diplomatic nightmare as a number of interested parties try to do likewise.