Okay, so I’m parsing what that situation in the Forges looks like right now.
It’s not… inaccurate to say it’s kind of like walking out of Bree and picking a fight with Saruman and the Witch-King. It’s not impossible, but it’s tricky. Sort of. Maybe.
So, first some various thoughts and advice from the book.
What’s the combat move if you don’t have Advantage?
Keep Them Busy, in most cases. Without an advantage to Finish Them with, you cannot hope to cause lasting harm. You can only Keep Them Busy.
The cases where you don’t roll to Keep Them Busy are when you have Custom Moves or Core Moves that let you do otherwise. Orcs don’t need an Advantage to Finish Them if they just break their weapon [for example]. If you don’t have any unique moves for dealing damage, however, Keep Them Busy is the basic move you will need to fall back on.
More on “Advantage” and Finish them…
Really, just read pages 261 and 262, but…
Advantage is mostly about fictional positioning, rather than anything concrete, so it’s difficult to define. It is both relative and arbitrary.
Relative. You have advantage if you are better than your foe. That’s it! Anything that makes you better than them can be an Advantage. A lot of lesser enemies and minions, you should be able to roll Finish Them right away. You don’t need to Keep Them Busy or earn your positioning every time. Only when it counts.
On the flip side, what if they are your equal, or worse, if they are actually better than you? Then you don’t get to Finish Them. You need to find a way to get the upper hand. And that can be anything - Keep Them Busy gives you a clear mechanical way to get Advantage, but it is not the only way. In fact, its not even the easiest way.
The other part of earning Advantage is that it’s a bit arbitrary. Whether or not you have it can change moment to moment, and what works against one enemy may not work against another. It also varies based on how you intend to Finish Them.
Your Advantage functions as an explanation for “why does this method work.” What do you need to Finish Them in this way? That’s your Advantage.
Now, the Overlord player has final say on what actually counts as an advantage. Simply surrounding a Cloud Giant or a pack of wolves may not be enough. Or it may be. That’s up to how dangerous the Overlord thinks you are, and thinks the enemy is, and thinks your method of attack is.
Overlord/Generals Strengths?
The Overlord can seem weak in the face of a big group of heroes. Keep Them Busy always gives Advantage, so if you just make six 7+ rolls, even a new party can beat the Overlord with three Keep Them Busies into three Finish Thems! Sure the team will take some hits but between all of you, you have the resources to soak up that damage. Right?
Well, no, its not that easy. The Overlord (and their Generals) have a lot of tricks up their sleeve to prevent them from being steamrolled by a dedicated fellowship.
Don’t forget the Overlord’s Basic Moves, like Heart of Iron and Twist the Knife[…]
Overlord has the tools to stay on top, as long as you remember them.
Also, your Overlord stats are indisputable fact, so long as they are undamaged. If you are Invincible, then you are actually, truly Invincible, and you cannot take damage until they can take that stat away from you. Until they confront you with your Weakness or else destroy the Source of Power that gives you your Invincibility, that stat will protect you from all harm.
Instantly Defeated Generals?
Unlike the Overlord, a General can lose to a single 10+ Finish Them roll. If they’re supposed to be so big and terrifying, working as an arm of the Overlord, why are they so easy to defeat?
Well, because they’re that easy in the stories Fellowship is based on. The hard part of beating a General isn’t the beating them part. It’s the reaching them part. Once the heroes reach them, they should be able to win.
So if you want to make your Generals tough, there’s three main ways to do it. Option A, give them troops. Option B, make them Tough As Nails. Option C, make them wily and clever.
A. If they have troops in the way, it can be hard to challenge the General safely. Use their soldiers to protect them, and make it hard to reach the General without dealing with their forces first.
B. If you make a General out of a threat that is Tough As Nails, like an Ogre, a Stone Golem, or the Warmonger, that gives them a buffer hit. When you want a General who can go toe to toe with the fellowship as a big threat by themselves, these threats are ideal for that purpose.
C. If a General is wily and clever, they can be very hard to get an Advantage over. Emphasize their fictional positioning, make them slip away easily, and regularly place obstacles between the fellowship and the General. The more frustrating they are to reach, the more satisfying the beat down will be. And lastly, Generals still have all the Overlord Basic Moves (page 178).
They can Forge a Bond with the fellowship by hurting them and the things they care about, then use those bonds to Twist the Knife or trigger Heart of Iron. These moves are key to making your Generals more than just another minion.
I’ll also note that the Generals can also use the Overlord’s bonds with the members of the fellowship to Twist the Knife and use Heart of Iron.
So, out of options A, B, and C, I took D, which is kind of a super-jerk version of B.
That is, made the General by giving the Threat to the World stat to one of the Overlord’s “organization” members - the Honor-Bound.
When to reveal enemy/set piece stats?
Unless a stat is Secret (pg 209), you should reveal enemy stats to the fellowship as soon as it becomes clear that enemy is a threat. Their stats and moves are intended to be public knowledge so the fellowship can size up what they’re getting into quickly.
With a set piece, you only reveal the section of the set piece you are currently on.
Right. So here we have Siflae, the General.
Honor-Bound: The most noble and generous of the bunch, they have a strict moral code they will not break. This code grants them unbelievable strength.
For My Honor: The Honor-Bound cannot be defeated or Taken Out. This stat cannot be damaged unless the Honor-Bound breaks their code. If they do, they are immediately Taken Out and will not fight for the rest of the scene.
Mercy: The Honor-Bound will always show mercy and compassion, even to their enemies. The first time a member of the fellowship honors their code, the Honor-Bound will honor a request they make. When the Honor-Bound is tricked, deceived, or betrayed by someone in the fellowship, damage this stat.
Unrelenting: The Honor-Bound deals damage to anyone Keeping Them Busy. The Honor-Bound deals damage twice to anyone who damages them.
Threat to the World: You threaten the world and all it stands for. As a Threat To The World,
you have immunity to a variety of moves.
When someone who is not also a Threat to the World takes direct action against something that is, they must Pay a Price to do so.
Thanks. This was helpful.
Also, I reiterate my intent to Keep the Fancy-Dancy Human – Edward, right? – Busy. 
Okay, so to break down attacking Siflae.
As far as I can see, Wynn’s default move for raging out and attacking Siflae is going to be Keep Them Busy. Finish them just isn’t on the table. They can’t be defeated, so that’s just not a move that will trigger.
To do that Wynn must Pay a Price to take direct action (every time), because she’s a Threat to the World, and her Unrelenting means that Keeping Them Busy will also damage Wynn, every time. Ouch.
For My Honor can’t be damaged/removed directly. You have to get them to break their code. What’s their code? I have NO IDEA. Which is one reason I needed to wait on this fight til next week.
Mercy (which also can’t be just damaged away - it’s got specific removal requirements) means Siflae is going to pull her punches. Does that mean she WON’T damage people who are affected by Unrelenting? Possibly! Could be she’ll just wreck all your gear and equipment instead, and maybe kill a couple uppity companions.
The author notes, on page 263/264 (MAN THIS WAS HARD TO FIND):
Another trick to make an enemy more interesting is to make one of their stats a drawback. The Organization uses this trick on every single member, where one of their stats is a drawback that makes them weaker at the start of the fight, but they become stronger as the fight goes on.
Stats stop being true once they have become damaged, so once the Mage Knight (for example) takes damage and marks their Arrogance stat, they lose the Arrogance debuff, and becomes stronger halfway through the fight. I highly recommend it. It gives them an extra hit without making them more complicated to deal with, while also making them more interesting enemies to face.
So both Ekki and Siflae are built that way, and they both have stats that make them easier to deal with… until they aren’t.
Based on THAT, I’d say Mercy totally make Siflae pull her punches a bit… while For My Honor keeps her from getting one-shotted.
Finally, Ekki of Bornaer is the Mage Knight:
Mage Knight: This warrior has no peer in combat of any kind.
Also true (because of an Overlord bond): Ekki is the most skilled of all my Harbingers.
Arrogant: Anyone who sings the praises of the Mage Knight can Keep Them Busy as if they got a 10+ without rolling.
Counter Spell: The Mage Knight cannot be Kept Busy or damaged by magic or ranged weapons.
Spell Sword: When the Mage Knight is trying to fight you, anyone who gets close to them must Pay a Price to do so.
So basically the cat wants to keep the mage busy while we do nothing against an invulnerable foe? Got it 
And finally finally, the gang of looters…
… led by a fast-talker:
I suspect Carabas can do quite a fine job singing the Mage Knight’s praises, thankyouverymuch. 
See, THAT is what I’m trying to parse.
I mean, they’re dangerous for sure. But Ekki can be kept busy and in general Siflae will leave people alone out of something like pity.
Facing Siflae is a meat grinder. Pay a price to engage, because of Threat to the World, and then even if she’s feeling merciful she’s wrecking your stuff just so you can keep her from … like… leaving (Keep them busy), for example. If you Finish Them knowing the 10+ only gets you a damage result, so you can take out a stat, you can soften her up a bit, though.
Mercy is tricky, because if a fictional maneuver that gives advantage also tricks her, then that stat’s damaged and things get ugly.
Unrelenting is not immune to damage, so you can at least deal with that. From that point on, you can keep her busy without getting double-dipped constantly. Threat to the World still hurts, because of needing to pay a price for every direct move against her.
Can you damage Threat to the World? Is that just a forth stat? I do not know the answer to that. Feels like no?
… Figure out what her code is and get her to cross it, and she’s taken out. It’s going be based on the nalres protectors in some way, but with a twist.
It’s kind of like the Dread Queen, sort of. Gotta take her in pieces.
Finally, full disclosure - these guys are tough because you’re like level 2 and it’s a good way to introduce the bad guys and make a big show down later more satisfying. Also gets things going. Drop some clues. Give Rowan some hints about what the overlord’s up to. That’s the initial idea.
I mean, with that said, though, if you take them down, you take them down. The overlord will be noticing you guys a lot sooner, which is probably not great news, but it’s still awesome.
I’m not protecting any NPCs, is what I’m saying, but I’m trying also to take the book’s advice.
I find that new Overlords are way too lenient with their players. It’s very easy to play softball forever,
and let the fellowship steamroll everything in their path.But the game plays a lot better when you get a little mean. Not a lot of mean - you should be fans of their characters, after all, and the fellowship will win eventually. But you need to be a little mean, so they have to work for it.
What I mean by this is, hit 'em hard. Each hero has a lot of tools to help them overcome adversity in their path, so you need to be that adversity. The heroes are tougher than you think, and you can’t kill them outright, so smack em around as hard as you want. Don’t you worry - they’ll get back up and push onward, because that’s what heroes do.
So there’s some of that as well. This is a good way to kick the tires on things really hard. 
Threat to the World is a move, not a stat. Hooray reading comprehension. 
Anyway. All of this is to say that I think you guys can put Siflae back her heels pretty quick (based on some stuff Bill had on Discord, Virens can open on her big time, especially if Wynn’s Keep them Busy has already bought them advantage. Finishing her off in a couple rolls is less likely, but ringing her bell pretty hard, right off the bat? Absolutely.
Honestly I’m worried I didn’t bring enough bad guys. 
Well that changes what I was planning on. Looks like Rowan is going to deal with the gang of looters.
I left my Moment of Truth in my other power armor 
This right here is the part that feels like it takes priority over everything else. Whether we can damage her other stats feels immaterial (and as you pointed out is actually bad for us in some cases) because as long as this is here, she’s on the scene until she gets what she wants. We’ll just keep taking damage by acting against her. All we can do is mess with her objective - which we don’t really know either.
The only way through her is to somehow figure out what she won’t do and make her do it. Can Wynn Command Lore about this? They already did, and the result was “she ought not be here but she is anyway”, so I don’t know how useful that’ll be. Letting the cat open his mouth actually makes us start taking more damage. Feels like a problem for Ann to solve.
I’m okay with this in principle, but I feel like it’s also not a great intro to the combat system for five new people, if our big target can only be removed from the field if we morally compromise her. We’ll see how it goes, obviously.
Fictionally, I know what this feels like, because I just went through this in FFXIV, a party of heroes fighting a monstrously powerful opponent who had a code of honor, and it went like this:
Okay. Lots to unpack there, and also some reading. So.
Figuring out her objective - Look Closely helps with that, I think.
I’m doing a close read, now.
Okay.
Now then:
Taken Out
When all your stats are damaged and you take further damage, you are Taken Out.
Okay.
So…
While that attribute on Siflae is undamaged, she can’t be killed outright. To me that’s ‘defeated’. And (kind of obviously) if that attribute is still undamaged, she can’t be taken out the “long/hard way” because that requires damaging all her stats, and that one’s intact. Got it.
So… Now this
Finish Them
Finish them… is not simply taking something out. Speaking totally literally, none of the results say “and now the guy is Taken Out.” Honestly, Taking someone Out is beating down all their attributes, and Finish them actually skips that entirely, in a perfect world/roll.
So what are the Finish Them results, and which are still on the table in the face of the Honor Bound?
So. Hmm. There’s stuff there.
I think it depends on what “defeated” means. If any of the Finish Them outcomes are a “defeat”, then her Honor-Bound stat says none of that will work. If “defeat” just means “physically overwhelmed in combat”, yeah. I’m interpreting it as “Finish Them is a tool for defeat”, but I’m happy to learn I’m wrong here.