Converting White Plume Mountain, Interlude: Blackrazor and Wave stats from WOTC

The main treasure in White Plume Mountain is the three artifacts - Wave, Whelm and Blackrazor. Way back when, Whelm got stats in Open Grave (since it belongs to the vampire Ctenmiir). Later on, Wave got stats in Plane Below, and WOTC previewed it here.

That leaves Blackrazor, the distant cousin of Stormbringer. WOTC ran a competition looking for good stats for it, and now they've decided to publish the winner. You can see the stats here.

That's all three artifacts covered, and two of them are free. I like it when other people do my work for me.

Skill Challenges With Organic Time Limits in 4E

So I've been thinking about skill challenges again. One tweak I've come up with is to add in an organic time limit, by way of two steps:

• Calculate how many rounds a normal skill challenge would take at maximum, if all rolls contribute either one success or one failure.
  
• Add the number of complete rounds to the number of failures needed to fail, but also add one failure per round that passes without the PC:s completing the challenge.
  

Example: A complexity 5 challenge requires 12 successes before 3 failures. Thus the maximum number of rolls is 14 (11 successes, 2 failures, the 14:th roll decides the outcome either way). A five player party would complete two rounds and be at their third when the challenge completes.
Thus, the modified skill challenge requires 12 successes before 5 failures.

If the PC:s only roll for primary skills without any tricks, this is mathematically identical to the core skill challenge rules, but it opens up several possibilities:

• You can have secondary skills that grant bonuses to primary skill checks, but rolling for them takes you closer to getting an "extra" failure for taking an extra round.
  
• Spending action points to roll for those secondary skills becomes interesting, turning skill challenges from a "free" half-step towards the next milestone into an actual encounter that drains resources.
  
• Skill rolls where success/failure count as two of whatever you rolled become more attractive.
  
• And of course, a counter-incentive to skipping your turn, since you're usually not better off not rolling now, even if your skills are bad for the situation.
  

I think I might try this for the next skill challenge I run.

Go To Hell

Nono, don't go. Go To Hell is the reason I didn't update last weekend. You dig through the earth, gathering coins to afford the entry fee to Hell. Weird, but an entertaining game. You also have to gather food (each dug tile makes you hungry) and health (tangling with snakes and bats hurts, you know).

So why did I tag this with "Roguelikes"? Just this feeling I get from it. You dig down through layers of the underground, using the terrain as a tool to kill the wandering monsters or avoid them. Sensible stuff works - you can put out torches with water, drown snakes with the same, drop rocks on creatures to splat them. And you, too, can drown or get splatted. Also permadeath - you get lives, but no saves.

There are some glitches, like splatting yourself with a boulder when you push it over an edge, but other than that I can definitely recommend you to Go To Hell.

On Cursed Items In 4E

Save Versus Death just joined the RPG Bloggers' network, and one of his articles is about cursed items in 4E. That reminded me that I should get working on my own article on the subject.

See, cursed items in D&D are weird with their universal badness. The One Ring was evil in all sorts of ways, but it was still a perfectly usable ring of invisibility. Stormbringer too... well, a perfectly usable sword of murderation +5. But in D&D, cursed weapons are almost all bad. You touch one, it gets stuck to your hand (head, body, whichever), and there's never an upside to the item.

(As an aside, Nethack handles this in an interesting way. Wearables can be cursed, non-cursed or blessed, but their effects can be good or bad, and have no bearing on the cursedness.)

Anyway, I figure that if I add cursed items to my game, I would want there to be an interesting choice to make. Take the classic Backbiter spear, for example. A perfectly functional +X spear, but on a natural attack roll of 1, it curves around to hit the wielder. Or the Armor of Arrow Attraction - I wouldn't quite use a -15 penalty vs ranged attacks, probably just say that the attraction cancels out the enchantment bonus of the armor against ranged attacks. Armor of Rage is a third option.

Even funnier would be an "Armor of Rage" that gave you bonuses for reckless combat behaviour and penalized careful tactics. Oh wait, that's the Berserking Sword.

(Seems there are a bunch of semi-useful cursed items anyway. Still, the concept is totally absent in core D&D4.)

Anyway, interesting drawbacks to otherwise useful items, not huge minuses making you want to get rid of the item ASAP. Those are my five cents on the matter.

Old-School Multiclasses in 4E - Are They Viable

AD&D had a rather different multiclassing system than 3.x and 4E. You picked two (or three) classes and leveled up in a gestalt of those two, splitting XP between both. 4E works a lot differently, but having just multiclassed my fighter into the cleric class (which is perfectly viable), I wonder what else works really well. So let's go through the multiclasses AD&D2 allows:

Fighter/Thief don't line up the prime stats nicely, but is still nice. A tempest fighter can get the dexterity to qualify for the Sneak of Shadows feat, giving him training in Thievery, and is probably using light blades that work with Sneak Attack. That's a nice burst of damage once per encounter. Going the other way around, a Brutal Scoundrel easily qualifies for Student of the Sword, giving him a +1 to hit with a (one-handed) weapon once per encounter (which also marks the target, but eh). You probably don't want to multiclass much further, except maybe to take utility powers from your other class - making a rogue a little tougher, or the fighter a little more sneaky.

All in all, playing a sneaky fighter is quite possible.

Fighter/Cleric is an excellent choice. Your prime stats can match perfectly, not that it matters much for the initial feat. A fighter can (and should) take Initiate of the Faith to heal an ally once per day. A battle cleric won't mind a +1 to hit once per encounter and an extra skill. Neither have to bend over backwards to get the stats to qualify either.

The future for a tough guy who didn't qualify for paladin school is still bright in 4E.

Fighter/Mage is a tough one. Neither gets much use out of the prerequisite for the other's multiclass feat, and the feats themselves are pretty non-synergistic. However, Arcane Power introduces the Learned Spellcaster feat, which gives you ritual casting. That and some useful wizard utility later on could give a fighter a dash of wizardry. He still has to scrounge up 13 Int for the feat, but that's doable.

Seriously, I'd recommend a Swordmage.

Mage/Thief No stat synergy here either, and the rogue has a harder time justifying both 13 Int and 13 Wis to qualify for Learned Spellcaster. I suppose a Wizard could be slightly interested in the Sly Dodge feat - giving him a bonus against OA:s.

I'd look into playing a Rogue/Warlock or even a Rogue/Sorcerer. Those feats aren't fabulous, but the stat requirements mesh well with what you already have. The Assassin is also relatively magical, though in another way than a wizard.

Cleric/Mage gets you a Wizard with a daily healing ability, or a Cleric with rituals (this one has to take some Int it doesn't need much). Again, you probably don't want to take attack powers from the other class, but utilities can be useful.

Cleric/Thief - no stat synergy, consider whether you want a healing Rogue. A cleric that can sneak attack with a light blade isn't all bad, but there's nothing amazing here.

Fighter/Druid... Fighters get no benefit from turning into a beast at-will, unless your DM is generous. Druids don't use weapons, and thus can't use the +1 from Student of the Sword. Hilarious. Battle Awareness - slap an adjacent enemy that shifts or attacks an ally - is at least moderately useful, but if your druid is in melee with enemies, they probably want to beat on him anyway.

Consider a Warden.

Fighter/Ranger doesn't even exist (thanks to Anonymous for pointing out that I had misread "Cleric/Ranger" in the comments), but it could work. Admittedly, the tempest fighter is close already, but what Ranger would say no to a +1 to hit once per encounter? A Fighter can pick up Warrior of the wild and kick arse with Hunter's Quarry. Stats line up perfectly.

Still, I wonder what the point is, fluff-wise, since the tempest fighter is already there.

Cleric/Ranger is the last of the two-class multiclasses. A ranger has the Wis to take the multiclass cleric feat, and a Battle Cleric will easily qualify for Warrior of the Wild (ranger multiclass) which doesn't have weapon restrictions and thus works just fine with cleric weapons. The character can then go on to take attack powers if he's going for battle cleric (both use strength), but note that many (but not all) ranger powers require two weapons, a beast companion or a ranged weapon.

Verdict: Cleric multiclass is as awesome as always, not huge potential for further multiclassing.

Fighter/Mage/Cleric is hard to do straight, since you can only take multiclass feats for one class. There is a background (Windrise Ports) that lets you multiclass into two classes, and of course the Bard can take as many as he wants (but then you have to start as a Bard). Given the background, starting as either Fighter or Cleric and taking the other two could be useful, as shown above.

Fighter/Mage/Thief has the same issue as the other triple-class, but works as stated above for class pairs if you can pull it off.

Verdict: Not shabby. Meleeist/Caster has issues that can be worked around sometimes, sometimes not. Druids are just weird, being melee beasts based off Wisdom. If you want to say that you're playing a Fighter/Thief, it is doable.

How Few Encounters Before Levelling Up?

So I've pondered how fast you can level up in D&D4. The base assumption is that the PC:s will have ten "encounters" before levelling up. That falls apart right away as at least the climactic fight should be higher level (and grant more XP). Let's say you use mostly hard encounters at character level +2 or +3. That's roughly 50% extra XP for each such encounter.

Then there are quest rewards. One major quest reward gives XP equal to that for one encounter. It's pretty easy to say that each adventure gives one of those.

Let's not forget skill challenges. They grant XP just like an encounter.

So if a DM wanted to level up the party rather quickly, it wouldn't be hard for him to design adventures for that. Let's say he wants to use the 5-step method, which actually has four legit encounters since the last step is the "aftermath". It might run thusly:

• Recieve a Quest in town - eventually grants XP for one encounter.
  
• The PC:s find their way to the dungeon through the wilderness - skill challenge, XP for one encounter.
  
• Entrance and First Rooms - one skill challenge, two normal-level fights. XP for three encounters.
  
• Setback - major fight. XP for one-and-a-half encounters.
  
• The PC:s work to mitigate the setback and get back in gear to take on the final fight. Skill challenge, XP for one encounter.
  
• Climax fight - major fight. XP for one-and-a-half encounter.
  
• Cleanup - skill challenge as the PC:s investigate what to do next. XP for one encounter.
  
  
• Total: XP for ten encounters.
  

There you go, new level after only four fights (and you can make that three by turning one of the normal-level fights into one more skill challenge in a puzzle-heavy dungeon). Who said D&D was only about fighting?

No Post This Weekend Either

December is going to be slow, OK?

The Shark is Drawing Nearer, I Must Not Jump

Nothing this Monday. Gearing up to finish the White Plume Mountain conversion, and after that I may have some things to say about 4E Village of Hommlet.

My Thoughts on Running Skill Challenges

So I recently ran a skill challenge in my campaign. Cool story bro, but what did I learn? Well...

1) Post-errata DC:s are just crazy low. Of course I should have checked over the PC:s skills. Anyway, the usable skills need to be either limited (so everyone can't use their primary) or the DC:s might need a bump. I was using normal DC:s almost across the board, I could have thrown in more easy and hard ones. Which brings us to point 2...

2) Encouraging people to roll. One player eventually decided to pass. No skin off my back, but it's a pity that the skill challenge system as written punishes people for at least trying to roll with a sub-optimal skill. I'm thinking of throwing in a time-limit (long enough that the PC:s easily beat it if they all roll) and maybe abolish failures, like I've rambled about earlier.

3) The time limit would also limit the availability of trying secondary skills. I had a few of them in the skill challenge, which granted bonuses to some of the primary skills. (they didn't grant successes or failures.) Theoretically, the players could just have farmed them for all the bonuses before tackling the primaries. They didn't, because they're decent, but in theory it's something to watch for.

Oh, about those skill DC:s: Normal DC:s are the baseline, of course. Those skills are just kind of there. Where it gets interesting is the other two kinds. There is a school of thought that says finding easy DC:s should be a reward for "reading" the situation - Intimidate is usually hard, but it could be easy if you are in a position of power. I can dig that, but I prefer the following alternative:

Hard DC:s give you something if you succeed. Maybe it opens up an easy skill, or grants a +2 to some other skill (with a normal DC).

Easy DC:s need to be earned, either by reading the situation or by succeeding on a hard DC. Or maybe failing the easy DC has harsher consequences than usual - -2 to a few skills or something.

I don't really want to go with double failures for easy DC:s. The party is three failures from utter failure anyway, it seems harsh to make that two just because they tried a certain skill.

Stream of consciousness over, have a nice day.

Luke Skywalker Must Die

Playing in a licensed setting that you like can be fun. However, there is the problem of metaplot. If you are running a game in the Star Wars universe, there are a band of rebels running about, blowing up the Death Star, redeeming one of the two Sith and killing the other one, that sort of stuff. There's the expanded universe, but meh. It's even worse if you want to play around in Middle-Earth - the fate of the world is hanging on the shoulders of Frodo Baggins and Samwise Gamgee.

So whack those guys. If I were to run a Middle-Earth Game, Frodo would have failed (or never been born) and the PC:s have (or be able to gain) access to the One Ring if destroying it is a part of the campaign. In Morrowind, the Nerevarine isn't a separate character - it's one of the PC:s. The Zelda game I've been pondering would start with King Link's funeral, as he is laid to rest next to his beloved Queen Zelda, dead two years ago. Kirk has retired. You get the idea.

The alternative is to have the players play the actual characters from the franchise, or something very close. It can be done well. There is a Castlevania game on RPGnet where the characters are Simone Belmont and other descendants of the official families from the Castlevaniaverse. I'm not familiar enough with it to comment, but I suppose it's more of a sequel to the actual games.

Screw Initiative

So I've been running a D&D game for a while now, and I've been trying out a houserule inspired by Ars Ludi. Namely, instead of rolling initiative for all distinct monster types in combat, the DM makes one roll for his entire side. After that, the players can go in whatever order they like between the DM:s turns. (Players still roll individually.)

So what happens is this:

• Initiative is rolled. Players roll individually, the DM makes one roll.
  
• The surprise round, if one occurs, is handled.
  
• Any PC:s that beat the DM on initiative can act. In whatever order they like.
  
• The monsters act in one huge block.
  
• It's the PC:s' turn again. With the looping initiative of 3.x and 4E, Players and DM now take turns acting.

As Ars Ludi points out, this nudges players into cooperating because it's never really "not their turn". Also, for play-by-post, it speeds up the game when players don't have to wait for each other to act. It's been working fine in the four fights we've had so far.

One downside is the potential for double-dipping: One character can go first in a round and hit a monster with an effect that lasts until the end of his next turn. Then he goes last in the next turn, letting all the other PC:s benefit from it twice. In practice, this isn't a huge deal (and monsters can sort of do this too, so it evens out), but one could enforce a policy that characters only get to benefit from such effects once. (That sounds like it would be annoying to track, though.)

Mike Mearls had a similar idea, with the added step that there is a "group cleanup phase" at the end of the PC:s' turn instead of each player's turn, where durations are tracked.

Hey, try it out. Three geniuses can't be all wrong.

Degrees of Success in Skill Challenges

Skill challenges in D&D is a nice concept, but as written, they are rather binary. You succeed or you don't. Not surprising, D&D hasn't really supported degrees of success in non-combat situations ever.

As one of my players has showed me, it's easy to fix. Post-errata skill challenges always require three failures to... fail. (Non-errataed challenges required a varying number.) That sets up a handy system for degrees of success.

• Success with no failures: Flawless Victory! As a DM, you'll probably want to throw in some bonus if the players manage this.
  
• Success with one failure: The baseline. If you are using pre-written skill challenges, the default result of a success can probably be substituted here.
  
• Success with two failures: You succeed, but there is a setback.
  
• Three failures: Failure. What it says on the tin. Pre-written skill challenges can have the default failure result inserted here.

The astute reader who's familiar with skill challenges may have noted that one can add "degrees of failure" based on how many successes the party got before failing. Unfortunately, the required number of successes varies, so it's not quite as straightforward. For me, four degrees are enough, but I might suggest a fifth:

• Three failures with no successes: Ballads will be written about this utter defeat. Don't expect this one to actually happen, the probability is pretty low unless the party is taking on overleveled skill challenges.

Let's do an example. The PC:s are hitting the library books before facing down some Elder Evil which is supposed to return to the world at the next solstice (in three days).

• Three failures: The PC:s find nothing about the Elder Evil. They'll just have to play the fight by ear when it arrives. In addition, they have drawn the attention of the Elder Evil's cult. Some cultists will interfere in the upcoming battle.
  
• Two failures: The PC:s find out where the Elder Evil will arrive (near a site sacred to Dagon, which is the temple ruin outside town), and basic information about it, but draws the attention of its cult.
  
• One failure: The PC:s know where the Elder Evil will arrive and basic information about it.
  
• Three failures: The PC:s know where the Elder Evil will arrive, and also finds some notes by a priest who fought it eons ago. (OOC, the players get to know its vulnerabilities and resistances.)

Legend of Zelda in D&D 4E

Another of my crazy ideas for future D&D campaigns is ripping off the Zelda: A Link to the Past. It's one of my favorite games from the SNES era, and it might translate well enough to D&D. Link needs to go away and be replaced by the party, but that's easy enough. The question is whether to make them a party with the Hero of Courage (Link in the canon) among them, add in the Hero of Wisdom (canonically Zelda) or just say that the Triforce of Courage actually picked five guys when Link was AWOL.

Either way, the party is somehow pulled into a quest to gather a bunch of plot coupons in order to beat Ganon and save Hyrule. Or something, it's not like I've planned the whole thing already.

Some elements have to be translated from the SNES game, of course:

• The Dark World. Definitely in. Gotta have a destination for that Plane Shift ritual, after all.
  
• Call a Rabbit A Smeerp. Of course, the names have to be kept.
  
• Religions. How to translate them to D&D? I'd go with reskinning existing cleric feats to fit with the Golden Goddesses.
  
• Stock Video Game Puzzles and Stock Puzzles. Big part of the game. I could see pushing puzzles working out okay, if you had to solve them during combat.
  
• Thriving Ghost Towns. Isn't this a feature of D&D modules too? Lots of implied citizens, but only a handful are ever seen.

So far so good, but the most important part is... 16-bit battlemats! Oh yes.

• Jaywalt has a great guide to editing such maps.
  
• The Video Game Atlas is a great place to get the maps themselves. You could probably do worse than scrolling down to Chrono Trigger and grabbing those maps while you're at it. Similar style.
  
• The Spriters Resource has all the monster sprites for you.
  
• Zeldapedia should cover most other stuff, particularly the lore. Helps me, since I haven't played any of the games after Link's Awakening, and only Link to the Past extensively.
  
• There's also Wikia Gaming if the former wiki doesn't cover something.

There you go. Partly a note to self, I hope it helps someone.

Ritual Availability In Towns

The availability of rituals just came up in my PbP game. What rituals are available for purchase in a given town? My answer is: All of them, up to a level limit.

My players are in Hommlet. It is a small village, but a natural rest point for caravans, and has a resident wizard (former adventurer), druid and priest. I decided that the players can get any ritual up to level 5 there. Higher may be available, but they have to go to bigger cities like Verbobonc to get them reliably.

So, something like:
Village: Up to level 5. Examples: Hommlet (Village of Hommlet), Winterhaven (Keep on the Shadowfell), most towns in "starter" modules for whatever version.
Town: Up to level 10. Example: Fallcrest (4E DMG).
City: Up to level 20. Example: Amn (Baldur's Gate II). I'd guess Waterdeep and Greyhawk too, but haven't read those supplements.
Metropolis: Up to 30. Mainly extraplanar places like the City of Brass, Sigil, etc.

Note that "village", "town" and "city" are roughly defined in the 4E DMG. "Metropolis" is not, but there are definitely places bigger than what the DMG calls a "city". Hope this helps someone.

Plane Trek, Part II - Tropes

So yesterday I posted about Plane Trek. I missed a few tropes, though:

• Space is an Ocean: It's almost a no-brainer. Most sci-fi stories use it, and while I haven't read Spelljammer, I've seen some ships, and they look more ship-like than spacecraft-like. (Most wouldn't float in water either, but they have sails.)
  
• 2D Space: Makes for easy mapping, if nothing else. I think the Astral Sea should be a few miles "thick", though, to allow for 3D maneuvering in ship battles without the hassle of mapping a spherical Astral Sea.
  
• Home Is Kinda Nice: The Federation in Trek is a pretty decent place to live. Adventure is out there, on the Final Frontier.
  (I couldn't find a TvTrope on the subject. Home usually sucks in fiction, after all.)
  

Plane Trek

One of my crazy ideas for a future D&D campaign is Plane Trek. I'm not a Trekkie by any means, having only seen the Shatner movies and Nemesis, but the idea of a party of D&D characters exploring the multiverse, meeting strange creatures/cultures and dealing with them appeals to me.

So what would the basic concepts be for this game?

• Diverse crew: Okay, the original movies had a bunch of humans and Spock (with other non-humans among the nameless crew), but The Next Generation has a Klingon, a half-Betazoid (granted, she looks human) and an android among the main characters. In a group of five characters, I'd probably rule that there can be no more than two of any given race.
  
• Worldbuilding: Races aren't from one planet with all the PHB races living in harmony. Each "planet" (actually some sphere in the Astral Sea) has at most two races (with some interesting relationship). Each player gets to detail the planet they're from. The "Federation" of known worlds then consists of the homeworlds of the player characters, with everything else a possible surprise.
  
• No material plane: The Normal World, Feywild and Shadowfell aren't their own thing separate from the Astral Sea and the Elemental Chaos. They're just planets among others, floating in the Astral Sea. Actually, the Elemental Chaos might be toned down a bit too.
  
• Planet of Hats: As with player races, monsters live in monocultures. There's a hobgoblin planet to land on and get in trouble, for example. Next week, the crew finds a sahuagin planet...
  
• Spelljammers ahoy: The high-tech of Trek becomes magitech. Spelljammers instead of spaceships, and everything else works mostly as usual in D&D.
  
• Overly obvious moralizing: Er... I'd skip that part.
  

No Post On Monday

Aaaand is this the point where this blog starts jumping the shark? Anyway, no post on Monday, as the title says. I'll try to have one up in the middle of the week instead.

I Am A Daredevil-Seeker

According to the BrainHex test, at least. The Daredevil likes Mirror's Edge, Canabalt and just going really fast in general. The Seeker wants to find stuff, so he likes Morrowind. Not a bad fit.

I'm mildly amused that both categories list Shadow of the Colossus as a favored game. I'll have to pick up that and a PS2 sometime.

Cost of Hirelings in D&D4

Looking over the costs of mounts from the 4E PHB and Adventurer's Vault, one finds that all the mounts - with the exception of the level 1 and 2 ones - are priced like magic items. Often items at higher levels than the monster's level.

This is quite understandable, as many of these mounts grant powerful abilities. The Rage Drake, for example, give its rider a +2 to hit and damage, which stacks with every other plus. Neato. A Dire Wolf, on the other hand, is just a dire wolf with no frills, so it costs the same as a magic item of its level (5).

The interesting part is extrapolating this to henchmen. A mount shares its actions with the rider, so it's not an extra set of actions on the field, just a power boost to the rider. Buying a henchman, on the other hand, would mean that there's an extra ally taking actions every round. Which is a huge boost.

But let's pretend for a while that it works. Many mounts cost the same as a magic item of its level+2. Applying the same reasoning to henchmen would let you hire a bandit (Human Bandit, level 2) for 840 gp (a level 4 item). Mind, this is a slavishly loyal bandit. For the cost of Bloodcut Armor +1, you get an ally that flanks with you and can unleash a Dazing Strike once per encounter. That's... a bargain.

Weekly rates make more sense than "buying slaves", since your adventurers will soon outlevel the henchmen. One might want to halve the cost and make that the weekly wage. Or if you find that the Bandit is indeed even better than an equivalent magic item, make the original cost his monthly wage - he'll eventually quit.

Finally, companion characters from the Dungeon Master's Guide II are probably better balanced as PC allies than creatures from the Monster Manual. PC and monster numbers are slightly different, after all.

Alternative Skill Challenges: Combat-Style

In D&D 4E combat, the PC:s fight whatever, and either win solidly, win with relatively heavy losses (of HP, daily powers etc), or lose (which means game over, or at least "you wake up in a cell".)

In a D&D 4E skill challenge, you either win or lose. No intermediate results, except for those special "wilderness travel" challenges where someone has to make an Endurance check to avoid being exhausted. The developers seemed to want to do more, but they didn't go further with the system in the first DMG.

A system I've been thinking of using is to divide up a skill challenge in "rounds" instead. Every round, each PC does something (makes a skill check). Once all PCs have acted, the "monsters" act. What this means is that each round that ends without the PCs having succeeded, something nasty happens. This could be a fight (drains resources), or something else. Failures aren't counted, the PCs are just trying to get the requisite number of successes in as few rounds as possible.

Lacking the patience to do the statistics for this by hand, I used Scott Gray's Dice Pool Calculator. Knowing that a trained or talented character has about 80% chance of success, I just have to look for the cumulative probability of getting the requisite number of successes. At first I assumed a goal of 5 successes, because that leaves a slight chance that 5 PCs could succeed before the end of the first round. If the party is smaller or larger, the requisite number of successes should be changed to mirror the party.

As the table on the right (click for bigger picture) shows, it's actually hard to get all successes in the first round, but the group is all but guaranteed to get them in round 2. Larger groups obviously have a harder time if everyone must succeed. If you really want to prolong the challenge, require twice the number of players in successes - they have a small chance of winning in round 2, and are likely to win in round 3.

Weirdness with large groups aside, this does do what I'm after. The PCs are likely to see what happens after a round they've failed, but they have a chance to avert it, and it probably won't happen twice. It seems to work, especially for "investigation"-type challenges, where the characters do something for a day (make a skill check each) and then the bad guys send assassins each night (Fight!).