the hope that he'll learn some interesting facts about Hell

This appears to be a misconception.

Nurah turns out to be the traitor, and leads us into an ambush by the Prophet of Baphomet - the Prophomet? - who is a huge fiendish minotaur.

This is Regill's - no actually that is in fact surprising. If it weren't surprising Regill would already have accused the frivolous halfling of treason. 

There is also a half-fiendish furious minotaur, two Babau one of whom is a caster, and a cultist who is apparently pretty good with a crossbow.

Between spell resistance and good Will and Fortitude saves, a Phantasmal Killer has about a one-in-eight chance of Just Killing that fiendish minotaur. That's pretty good, actually. Twelve-and-a-half-percent chance of dropping a powerful enemy in its tracks? Worth a shot.

That can't possibly be balanced!

(Glances up from the latest Report from Otolmens) Oh, another one? Put it in the pile over there, I'll sort them later.

Regill is aware that some people believe 1d6 is a bad damage die; that you really want 1d8 or even 1d10. Those people evidently have not considered how modifiers work. In particular, we have:

Strength: +2
Prayer: +1
Enhancement: +2
Weapon Specialization: +2
Weapon Training: +1
Unrelenting Assault: +4
Piranha Strike: +6
Smite Chaos: +2

oh and also an additional 2d6 Holy damage from using this named axiomatic weapon on a chaotic creature. Once you're up to 1dN+20, the value of N is not all that relevant. Indeed he can roll a 1 with perfect equanimity.

Yeah! What he said! Only with Smite Evil!

Heal.

Hah! Back to full hit points! How's fighting a Cleric 12/Monstrous Humanoid 6 working out for you lot?

Shrug. Regill notes that this move concedes all initiative to the opponent; the equivalent of retreating one's improvidently-advanced queen back behind the starting pawn line. Hit points are only one resource; tempo is more important.

So that'll be a Strength/Smite/Strike/etc Full Attack, then.

Well, fu - 

Oi! What's the use of handing out DR10/Adamantine if you're just going to give the crusaders' Smites the ability to bypass Damage Resistance?

The petitioner is once again reminded that this court does not have jurisdiction over bug reports and especially not over alleged "balance issues". This court is, in fact, getting a bit tired of petitioners arguing about "balance". The only balance that applies are those between Good and Evil, and between Law and Chaos. 

After the fight, how do they feel about meeting the informant who sent them the warning about the attack on Kenabres?

Oh come now. A pretty lady chained up in the dungeons? Who doesn't even try to hide that she's a succubus? That's the oldest trope in the Player's Adventurer's Handbook!

Abramo is not familiar with that work, or that trope. In general he feels that people stored in an enemy's dungeons are probably there for a reason, and can at least provisionally be classified as enemies-of-the-enemy. Especially when he does in fact recognise the voice. He's rather curious about why the demons would choose to lock someone up, though, as opposed to tearing them limb from limb in a spectacular public execution. That seems more their usual mode.

Look Arueshalae has read the Handbook too. How about she doesn't offer to show them a secret way into the enemy headquarters, or suchlike, but just asks to be let out of the cell and go away?

Truthfully, he has absorbed rather a lot of the local anti-demon prejudice in the past few weeks; they do, actually, seem like an untrustworthy, backstabbing bunch. But, to be fair, if one of them is reliably backstabbing its own kind, well; enemy of my enemy, and all that. And besides, they did just take down two fiendish minotaurs in fairly short order; a single demon ought not to be an immense threat even if it attacks them upon being let out. Actually, now he thinks about it, to the extent that a succubus is a threat, it's not particularly one that depends on being out of the cell; the mind-control magic works just fine on anyone it can talk to.

And they still have Protection From Evil up, and he doesn't actually feel particularly compelled to listen to her words...

Oh, very well. He took a chance on Woljif; he'll take a chance on this one. It is the nature of correct judgement that it must remain suspended until the data is in; and sometimes you have to take a risk, to gather that data.

Indeed! That's how you do science! But we really ought to find another succubus prisoner to be the control group. Or better still, how about that halfling over there?

The halfling has been driven insane by torture, and attacks.

Arueshalae doesn't.

Hmm. What does it indicate when the control group shows the expected behaviour, and the intervention group doesn't?

The assault on Drezen is very bad.

Abramo has not been impressed with demon armies in the open field. Individual strength and resilience do not actually do much to make up for the formidable push of cold-iron pikeheads thrust forwards by disciplined men in well-ordered ranks. In the warren of garbage-choked alleys and decaying houses that is Drezen seven decades into the occupation, it is a very different matter. In these close quarters every Dretch is a gas barrage that stops infantry attack cold; every Brimorak a mortar battery zeroed in on a crossroads, and making it impassable to unarmoured men. And as for the greater demons, the Vrock and Derakni whose droning screech can render a platoon helpless... they are not invincible, if you can just get at them from more than one direction! In the open field, with squads and platoons free to advance where the greater demon isn't and expose a flank, the Crusade can defeat them readily enough. But in a narrow street that limits them to frontal attack, from behind an improvised barricade of torn-down houses and dead horses and less wholesome things, a Vrock can stand its ground for hours on end, and heap up enough corpses to make a second, ghastlier barricade.

Abramo knows what house-to-house fighting can do to an army; there was Cairo, and the three-year siege of Constantinople, and even to the very end the Danes held Viipuri against all the power of the Imperial Japanese Army. And that was in a symmetrical conflict, both sides wielding the same weapons, where the attacker could at need manhandle a six-pounder gun into sight of a stronghold and blast it over open sights! And even so, every city that could not be bypassed shattered regiments and divisions; individual factories and neighborhoods became famous fortresses in their own right, whose defenses passed immediately into myth with Thermopylae and Masada; whose fall had the same electrifying effect as the sinking of a dreadnought, or the death of a renowned general. Abramo cannot afford for that to happen here; the war is just too small. In the terms of his own world, his entire army is three understrength regiments - he cannot well call it a division, for he has neither artillery nor a transport pool! - and he cannot expend a single one of them taking any of Drezen's strong points. There are no waiting millions to conscript into these ranks, if he carelessly spends their lives in bloody head-on attacks. 

There is no artillery, no tanks, no sky-blackening thousands of bombers to lay a resisting city flat and break the hearts of its defenders. Abramo uses what he has: His tiny special-operations strike force, backed by his own magic. Regill and Seelah can take down a Vrock, darting through the skull-shattering screech that kills ordinary infantry to slash at the flanks after Lann's arrows strip away the blurring-dancing-shimmering Mirror Images, in spite of the splitting headaches that looking at them for more than a few seconds causes. The Brimoraks are not so formidable as all that against Sosiel's Mass Protection From Fire. The Dretches remain a nuisance - no man has understood the horror of chemical weapons, who has not seen an Enlarged paladin reduced to helpless Enlarged Vomiting all over a narrow alley - but exposure has built some tolerance, and usually only one or two of the companions are affected now. It can be done, they are doing it.

...at a price. The city is full of chokepoints, which become literally choking points when the Dretches do their work. The strike team is immensely deadly against any one of them, when prepared with a full load of spells; but they cannot take the time to so prepare against every barricade, every crossroads, every house full of cultist archers led by a Brimorak. They must take the city quickly, before the enemy can mobilise the still-greater demons deeper into the Worldwound.