As I've been saying for a while, I want to run Mists of Bilehall and The Chains that Rust as an epic undead campaign for my players, and although that's still some ways off (we have at least another full campaign to go through before that can happen) I can finally start tinkering with it seriously, since I just acquired the last pieces I was thinking I'd need (with the added bonus of also having The Trollfens and Bonds of the Wild , which was unexpected).

Anyway, not all quests in Mists of Bilehall or The Chains that Rust features all-undead opponents or similar. This is perfectly understandable, albeit still annoying, since each expansion only ever assumes you have access to that expansion and the core set. With that in mind, that's why the quests of the expansions feature Goblin Archers as soon as ranged opponents are warranted - it's the only base "rank and file" ranged units available. More appropriate, for example, would probably be Skeleton Archers. But Skeleton Archers are from the Treaty of Champions, so they're not assumed to be present.

So, going through the Mists of Bilehall and The Chains that Rusts quests, I'm going to look for instances where I would want to houserule one of the listed monsters into another monster. For those select quests, I'll also consider possible open groups.

What I'd love would be if someone that also has access to Mists of Bilehall and The Chains that Rusts would double-check so that these changes do not interfere in a major way with the narrative , the balance , or the rules of the encounter itself . I want to make these changes to the encounters, but I don't want the encounters to be broken or otherwise massively unfair.

As the Overlord myself, I'd rather err on the side of caution - that is, I'd rather the encounter becomes harder for me than for the heroes, since I am the one enforcing these changes.

So without further ado, these are the basic changes I was thinking of making:

Fear Unshackled, pg. 16 (MoB):
Replace Goblin Archers with Skeleton Archers. I'd like to replace the Merriod, but can't think of anything fitting the narrative, the marshland theme, and still likely to be balanced, so I've elected to keep it.

1 open group (Wilderness, Cursed) in the Marsh; I'm thinking regular Reanimates crawling up from the swamp, or Plague Worms.

Shattered Schemes, pg. 20 (MoB):

Replace Flesh Moulders with Dark Priests. They perform the same basic function(s) and both can heal.

2 open groups (Cursed, Civilized); I'm thinking Reanimates, and then Skeleton Archers, plain and simple.

Juliden's Keep, pg. 22 (MoB):

Replace Master Shadow Dragon with Master Crypt Dragon.

1 open group (Building, Civilized) in the Library; I'm thinking Wraiths or Crow Hags.

Hallowing Fire 2A, pg. 26 (MoB):

Replace Flesh Moulders with Dark Priests.

1 open group (Wilderness, Hot, Cave); this one is really hard. This open group is only added conditionally, coming from the darkstone statue, so I'd want it to be a wraith or crow hag or a shade, but nothing qualifies. Luckily, Shambling Colossus from TCtR has Wilderness, which is strange, so; Shambling Colossus, I guess.

Legion's Hunter, pg. 12 (TCtR):

Replace Goblin Archers with Skeleton Archers. Again.

1 open group (Wilderness, Water, Cold, Cursed) on the Pool; I'm thinking Bone Horrors, hitting the heroes from land and keeping them in water.

Freedom From Flesh, pg. 14 (TCtR):

Replace Flesh Moulders with Dark Priests. Again.

2 open groups (Cursed, Building); here I was considering actually using Sorcerers, but Wraiths, Shades, Reanimates and Skeleton Archers all sound like they'd fit in very well. Since there's a couple of different ways at least the second open group can enter the map, it's a pretty hard choice.

Halls of Phetra, pg. 22 (TCtR):

Replace Goblin Archers with... Skeleton Archers!

1 open group (Building, Cave, Cursed, Civilized) in the Chapel; honestly, so many good choices here. Dark Priests would probably fit the best, narratively, but at this point they're so common it could be boring. Wraiths, Shades could also fit, but I'm actually leaning towards Dark Minotaurs.

Another option here would be to actually replace the Zombies with Shades (both are 2/1 3/1 4/1) and take Wraiths as the open group, truly keeping in the spirit (no pun intended ) of the presented narrative. However, Zombies have some very specific and pronounced mechanics (notably, they are very slow) so changing them into Shades could have some serious repercussions, so I'd like some input on this idea in particular.

Additionally, I could also imagine replacing Goblin/Skeleton Archers with Crow Hags, but at that point, I have no idea on what planet the balance of the encounter would be - I just know that it'd be a 100% spirit-based encounter, which would be pretty cool.

Profane Nexus E1, pg. 26 (TCtR):

Replace Flesh Moulders.. with Dark Priests. Again. They really like their Flesh Moulders.

1 open group (Building, Wilderness, Cursed, Water) on the Graveyard; I'm thinking Bone Horrors, Broodwalkers or even Crypt Dragons. Anything like that would work on a graveyard, really, and I'd want something other than Reanimates/Skeleton Archers.

Profane Nexus 2A, pg. 28 (TCtR):

Replace, you guessed it, Flesh Moulders, with, you guessed it again, Dark Priests.

2 open groups (Mountain, Wilderness, Cursed, Water), both deployed by special rules to Library or Tower Stairs. Here, practically anything could be good, but I'm actually leaning towards.. Flesh Moulders, since I can't use Sorcerers, but honestly, Skeleton Archers or Reanimates would work just as well. Anything cult-y or rank-and-file-y would fit.

That's it , really.

Overall, MoB/TCtR will likely make for a really great undead-centered campaign, with very little effort. The one thing that consistently stand out are Flesh Moulders and Goblin Archers, easily replaced with Dark Priests and Skeleton Archers, which, that I can see (which is why I'm asking for help) would have zero meaningful narrative/balance impact.

Especially TCtR stand out in that every single quest and encounter (most quests in both MoB and TCtR are are single-encounter, sans the finales (or rather, in one case, the Interlude, if you do it as a single campaign, interestingly enough, meaning that MoB/TCtR is the only (afaik) campaign that has a two-part interlude - especially interesting since all other quests are single-encounter) has the Cursed Monster Trait, meaning that if all else fails, open groups can at least be something Cursed, which includes most undead monsters.

Thoughts? Having gone through the quests at a glance, the one I'd be most interested in comments on are the potential changes to Halls of Phetra, since the changes could be pretty major, but also very thematically satisfying. Also, if you know of any quests that stand out as strange or that you think should be revised in some way as well, I'd love to hear about it. At a glance, I think it could be hard to find fitting monsters of Troubled Waters (pg. 18, MoB), with there being a whole 3 open groups and with only access to Wilderness and Cave. Barghests, Plague Worms, Shambling Colossus, maybe?

Any time you replace Goblin archers with skeleton archers, there are two major things to consider:

1) Scamper. Goblin archers can't be blocked by heroes, and skeleton archers can.

2) Speed. The goblins have a speed of 5, skeletons a speed of 4.

These both especially make a difference when the OL's objective is to get the goblin archers somewhere (as is the case in Fear Unshackled, less important- but still a factor- in the other quests you mentioned- mostly in Halls of Phetra).

For plague worms, the ability you're introducing which has the biggest potential to throw the balance is "Burrow." Moving the heroes isn't a big deal if you already have the option of bringing in "Bone Horrors" (since Lash could also do it), but the ability to bypass elevation lines and sludge could be a huge advantage. Fear Unshackled and Troubled Waters have a generous helping of Sludge, and some elevation lines.

Juliden's Keep is OK because the master shadow dragon doesn't have shadow anyway, but the ranged attack on the dragon is something to consider.

For Halls of Phetra, the open group doesn't reinforce, so hopefully the impact isn't gigantic. Shades can teleport, which (while the dispossessed already can) is problematic. Dark Minotaurs might be a better bet.

Played Fear Unshackled last friday, and decided to give skeleton archers a try instead of goblin archers.

Overall, I think it changes a bit the strategy you'll (both the overlord and heroes) employ during the mission.

The heroes spent the first round dealing with them (without success), and afterwards simply decided to block their path on the intersection.

Since they're harder to kill, and also that all their attacks have pierce 1, I decided (as the overlord) to use them to attack. By the end of the mission I had only 5 fatigue tokens.

It was a tough match, the heroes managed to take all soul tokens from Zarihell and bring her to 9 health... and then they got overwhelmed.

Thanks a lot for the feedback. Like I said in the OP, I'm a lot more OK with the overlord suffering a bit than the heroes. I'm more worried about screwing them over, than me screwing over myself.

When I do end up running Halls of Phetra, however, I think I will make it an all-spirit encounter, balance be damned, and then see how it turns out. It will probably be a long time until I can get around to doing that, but I'll make sure to check back whenever I do.

Oh, and I forgot to say. I used Reanimates as my open group.

I remember regretting half-way through the mission. They didn't do much in terms of damage, all they contributed was in offering Zarihell cover against ranged attacks, and as fodder for the raven flock (the master reanimate won't take the damage if enough reanimates are standing nearby). The sludge makes maneuvering really hard on that tile, and since their movement is so low, they couldn't do much.

Oh, and I forgot to say. I used Reanimates as my open group.

I remember regretting half-way through the mission. They didn't do much in terms of damage, all they contributed was in offering Zarihell cover against ranged attacks, and as fodder for the raven flock (the master reanimate won't take the damage if enough reanimates are standing nearby). The sludge makes maneuvering really hard on that tile, and since their movement is so low, they couldn't do much.

I was considering reanimates too, but with that in mind, I'll probably opt for the Plague Worms - just to push the heroes into the sludge. With Burrow, the sludge won't bother the Plague Worms half as much (they've got a movement of 2, anyway; Borrow allows them to effectively move 4, by expanding out of the edge of the 3rd space), and you should be able to force the heroes to effectively lose several turns. The only issue is that the Plague Worms won't reinforce, so they might not live that long.