It’s pretty easy to model a damage-dealing challenge. On some level, that’s what almost any trap is. Consider the classic “Hallway full of darts” – it makes an attack against each player after they act for some amount of damage and players try to dodge through, spot pressure plates or disarm the mechanism. Right off the bat this is something that’s pretty easy to model as a combat challenge, with the player’s able to inflict damage by trying to circumvent (dodge), Understand (find patterns, stay off pressure plates) or manipulate (disarm). Smashing is probably off the table since hitting the walls with a sword doesn’t help much, but that’s fine. Player might be able to use acrobatics or athletics to dodge, perception, dungeoneering or maybe even stealth to try to avoid triggering it, or dungeoneering to try to disarm it.

The DM sets the difficulty of these things by setting the defenses, which helps dictate the shape of the challenge. In many challenges, one path might be easier than others (so it may have a weak defense). Alternately, a challenge may have one best solution and many ok solutions, in which case the approach that supports the most skills will have the highest defense, while the specialized defense may be lower. In the case of the dart trap, Understanding supports lots of skills, so that might mean a high will defense, but only one skill is useful for manipulating, so the fort defense might be the low one.[1](It’s also entirely reasonable for the DM to give the challenge vulnerability to certain approaches. Vulnerability 10 (Disarm) might be a little awkward on the page, but the idea is pretty workable).

All very easy, but it gets more complicated when we get out into the realm of other challenges, ones with consequences that are less easily measured in hit points. This is where the GM really needs to put some thought into things because this is probably the single most important part of designing a good challenge, though this may not be immediately be obvious.

What the GM needs to decide is what this challenge threatens and determine how to measure that. The easiest way to do this is to express this in terms of some kind of currency. Just as Hit Points are a currency for the health and well being of the characters, there may be other currencies to reflect other important things.

There are a few existing currencies within 4e beyond hit points. Treasure (both gold and magic) and XP are both good examples. I’d be very hesitant to threaten a character’s XP with a challenge, but it might be reasonable to threaten money, such as with a challenge that imposes repair bills. Dark Sun also introduced the idea of “Provisions” as currency, and that makes for a GREAT currency for outdoor challenges over time.

However, there will not always be some existing currency for you to use, in which case the GM’s going to have to think of something to use that reflects the situation. This could be something concrete in the situation (like, each round, one of the seven sentinels falls) or it may be an arbitrary pool of points (the resolve of the citizenry has 100 points, but the propaganda of the cultists is doing damage to it every round).

As a math or game exercise, this is easy enough to do, but the trick is to make sure the currency is something more than an abstract exercise. The first trick of this is to realize that there are two main ways to handle currency and you don’t want to mix them. The first kind has intrinsic value, like gold. Every time it’s diminished, the owner loses out on something, and a near win is still going to be very costly. The second kind works as ablative protection for something else, like Hit Points do with health. The actual loss of the currency doesn’t cost much of anything, but if the currency is completely expended, then something very terrible happens.

Intrinsic currency is usually less valuable in total than ablative currency – that is to say, losing all your money may stink, but not as much as a sucking chest wound. That’s important for GMs to bear in mind when deciding how to structure the currency for a challenge. Intrinsic currency is useful when a challenge is supposed to be inconvenient and to burn through resources. Ablative currency is better for the all or nothing.

There’s a temptation to mix the two with a sense that doing so increases the stakes, and thus the excitement and tension of the challenge. COnsider launching attacks against the PC’s troops. If damage removes troops, that’s intrinsic (because it diminishes the resource) but it also feels like an ablative challenge because if they lose, all the troops are lost. That’s dangerous and tricky, since it is more likely to increase frustration – for players it can feel like they’re in a lose-lose situation. The currency loss hurts badly enough that the whole exercise feels pointless.

Sometimes that’s desirable, such as to underscore a very bleak situation, but that should be _rare_.

One alternative to consider in all this is to give the PCs SP’s, just as they have HP. That’s actually a very workable model, and if you can get the table to accept the idea that these all work as measures of how long the player can stay functional rather than concrete measures of health then you’re ready to rock.[2] That is a little bit of a weird idea, though, so I’m not counting on it.

Anyway, the question of how the challenge hurts you back is only one issue on the table. Tomorrow, we need to figure out when and where it gets a chance to do so.

1 – When building a challenge, the question to ask is whether you’re trying to engage the group equally or if you’re looking to give one player a chance to showcase his particular strengths (like the classic thief disarming a trap or wizard deciphering arcane runes). That can give you

2 – You can even keep them the same as HP. Yes, there’s a temptation to switch stat from situation to situation, but that invites bookkeeping pain. Instead, I would suggest that endurance is the one truly unifying element required for all human endeavors. It’s physical necessity is obvious, and for mental exertion I would suggest that while wisdom is all about that burst of will and focus that lets you shrug off a mental assault, constitution is still what you lean on to decide not to have that cigarette. (Yes, this is a rationalization of a mechanic. I’m ok with that).

If you spend time designing monster for 4e you will quickly discover that while some parts of the design are pretty standardized, like hit points and defenses, others are much more art than science. Specifically, monster abilities follow few hard and fast guidelines, and are instead something you come up with by mixing your ideas with a rough overview of the abilities of monsters at a similar level.

This is important because “combat-izing” challenges requires a similar mindset. The simple reality is every challenge will be a little bit different. In many ways, creating a challenge is more akin to creating a monster (where elements must be created from scratch) than creating an encounter (where existing elements must be arranged cleverly). This may seems like a very fine distinction, but it’s a critical one.[1]

We’ve already got some of the most important elements of making challenges feel more like combat – tools for pacing, acting and determining victory – but those are all from the perspective of the actor (in this case, the PCs). To handle the rest of the model we need three more tools to round things out: Sequencing, Situation and Consequence.

In combat, these handled by initiative, the battle mat, and the various monster attacks and actions. Ideally, we want some equivalency with these ideas (because they’re familiar and comfortable to players) but we don’t need to adhere so closely to them that we trip ourselves up.

Sequencing is the easiest to get out of the way: initiative is a very flexible concept since it’s ultimately just the order things happen in. There are basically 3 possible models here:
1. Roll initiative as normal (possibly for each challenge element)
2. Go around the table, then the challenge acts
3. Challenge acts after each player acts.

These are pretty self explanatory, especially the fact that #3 is much more dangerous from the player’s perspective. I’m not going to dwell on this for the moment because I think this is the easiest element to handle, but may also be the most situational. If nothing else, it’s just not going to make sense until we have the rest of the model in place.

Situation, on the other hand, is pretty critical. In combat, the map serves as a passive answer to a lot of critical questions. Yes, there’s range and counting squares and stuff, but there are also broader situational things like who’s in play or what areas are threatened (and by what threats). We probably would not want a literal battlemat, but at the same time, we want to provide enough ambient information to keep things clear for the players. That suggests that a more abstract model, such as diagram mapping or a card-game model might be in order.

Lastly, consequences are probably the most nuanced of these, in part because of their role. While we’re streamlining sequencing and initiative, we’re actually _enhancing_ consequences. Combat consequences are generally limited to hit points and death.[2] In a challenge, the consequences are far more wide ranging. Certainly, the personal health and safety of the characters may be at risk, but many challenges will threaten other things entirely. Whatever it is the challenge threatens, there needs to be a way to express it, probably through the depletion of some sort of currency (of which hit points are an example). So that introduces two issues: representing the currency at risk and then representing _how_ to threaten it (that is to say, how to damage it).

So, the next step is to break those elements out, and run through how to handle them.

1 – This is also fairly early thinking on this idea. If this gets some traction and use and there is ever a substantial body of example to reference (akin to a monster manual) then the dynamic will change, as challenges can be built out of various “problems” which have been used and documented.

2 – Statuses occupy an interesting niche here, in that they are consequences, but only in a very short term sense. They don’t get taken away from the fight, though they may have a profound impact on the ultimate outcome of the fight. Curiously, that’s more akin to a situational element – a status is not a piece of geography, but its impact on the fight is very similar. It forces decisions and drives the direction of action. I think there’s a place for statuses (and status-equivalents) in challenges, but for this reason I think it belongs under situation, not consequences. That said, games like Mouseguard have done a great job of illustrating ways to handle long term status-like effects, but that may be a bit too far out on a limb for this.

First, 2 Realizations:
1) SP is also used for currency, but to heck with it, I’ll keep using it for the time being. This whole thing is going to need a big language cleanup by the time it’s done.
2) Rather than 1d6/1d8/1d0 damage progression, it probably makes more sense to use the light, medium and heavy damage progressions from page 42. I’ll still use the previous model for illustration because I can remember it, but at the table, I’d totally go with the other approach.

All right, so with the basic concept in place, let’s start with how to actually build a situation. Assuming a default monster HP level of 24 + 8 per Level, it’s pretty easy to do a quick XP/budget conversion. A single 7th level monster is equal to a situation with 80sp. That math is pretty easy. What exactly to do with those 80 points is a little more interesting. It’s effectively a budget with which to create problems, or to reflect player action. For example, breaking into the enemy camp might be an 80 sp challenge, or you might break it down into 4 20sp guards who need to be overcome.

Now, one fun part of this is that, in theory, SP can be converted 1:1 with hit points. That is to say, if I’m running a fight with an elite opponent with 250 hit points, I could take 50 of those points and turn them into SP and use them to make the fight more interesting. In strictly literal practice, there are some problems with this: monster hit points are not actually consistent with this and the budgeting will not always be intuitive. Much the same way traps can sometimes be turned against enemies, there are going to be time it makes sense to keep hitting the situation rather than the monster.

And here, right here, is the critical decision point. Those are real roadblocks, and not every player would be comfortable going past them, and as such, it’s entirely reasonable to say this model won’t work for you. No harm no foul. But if you can tolerate the loosey-goosey, GM improvisation this demands then stick with me. You can do some cool stuff with this.

First, don’t worry too literally about monster hit points. If you bring a monster in as its own encounter element then you know what the rules are for that. It has a certain number of hit points and costs a certain amount of XP. No problem. But when you throw in a monster as part of a situation, its hit points are just a part of the situation. To illustrate, consider the 20sp guard. We can “beat” him by doing 20 points of damage (progress) with stealth, but if it turns into a fight, he’ll have 20hp (or more aptly, 20 hp minus any reduction in sp from earlier skill rolls).

This rolls into the second thing: If you have a monster that also has a challenge component, don’t worry too strictly about distinguishing it’s HP budget from it’s SP budget because – and this is the kicker – really they’re the same thing. Consider, for example, the group being attacked by a goblin horde (treated as one creature). The players can fight – just keep killing goblins until they stop – but maybe they want to try to scare them off (Intimidation). If a player wants to engage the “situation”, then he might use intimidation to reduce SP, which comes out of the horde’s HP budget.[1] Something similar might happen when you try to reason with someone you’re fighting, trying to convince him not to fight.[2]

This interoperability with hit points would not work on its own, but there’s another important element of challenges – the difficulty. How hard is it to do this stuff? To answer that, I ask the much more important question: What are you going to do?

There’s an instinct to answer “Use this skill!” but that overlooks something important. The goal here is to open up _actions_, which skills represent and support, but do not define. That may not be immediately clear, but pull up to a higher level. When faced with a challenge, there are a few ways to approach it, but in the abstract, they break down into four different approaches:

First, you can try to circumvent it. You can elude it, go around or otherwise avoid engaging it on its terms.
Second, you can try to manipulate, control or wrestle with it. You meet it head on and try to bring it to heel.
Third, you can try to understand it. Study it, and use that knowledge against it.
Fourth, you can hit it. Hard. Possibly repeatedly.
Fifth, you can suck it up.
Sixth, you can run away.

Now, I want to set aside #5 and #6 right away. Both of these might call for skill rolls, but neither actually helps get past a challenge, so they’re outside of the scope. #6 might be a _different_ challenge, but that’s it own thing. #5 is the desperate hope that the other guy will get tired punching you. There are situations where it’s appropriate, such as when the challenge is on a time limit or otherwise constrained, but in that case, it’s under the auspices of what bad things the challenge is doing, and that’s another topic. So, in short, they’re off the table here.

#4 is easy. D&D already handles that really well.

#1-3 is the trick. You will generally use a skill to do one of these things, but there’s no 100% correlation between which skill is used what way. There are some logical limitations, but they’re situational. When you need to travel through enemy territory, Survival might be used to get around enemies (circumvent) or it might be used to try to find the best route (understand). Viewing actions through this lens of what they accomplish makes them more versatile and interesting, and definitely I smore satisfying than the “skill first” approach where a player says “I use Survival!” and upon being asked “Do do what?” has to scramble for an answer. [3]

Experienced 4e hackers probably have already seen where I’m going, but I’ll lay it out here. The 4 approaches correspond to the four defenses used by 4e. Thus:

1 – Circumvent – Reflex
2 – Manipulate – Fortitude
3 – Understand – Will
4 – Smash – Armor

While this creates a little bit of a shift in how to handle some situations (Stealth being an attack vs. reflex rather than a roll vs. Perception) it streamlines things a lot and, more importantly, makes it VERY easy to extrapolate a challenge from a monster (or to fold a monster into a challenge).

So, for example, If the Warlord of the Orcs is hunting for you, the GM could create the hunt as a situation, drawing from his HP to budget it (or just creating it), and set all the “difficulties” of the hunt (which is to say, its defenses) using the Warlord’s stats. In effect, by evading the hunt, they’re fighting him by proxy.

Now obviously, there’s more to cover. The big one is, of course, the bad things that challenges can do to you in return – without that they’re pretty toothless. But that, I think, is something for next week.

1 – Yes, this effectively “weaponizes” skills (which is part of why I want to sync up with the page 42 damage expressions. A strict mind could view these as repeatable stunts). This is an idea I’m fond of from its success in SOTC fights as a way to help all players feel able to contribute at all times 9and ot encourage them to find interesting ways to apply their skills). This is maybe a little less relevant to 4e where there’s less of an idea of a “non-combat” character, but it can still help.

2 – This may immediately raise some confusion of how to handle fights where a lot of HP and SP damage has been done, but 4e actually solves that VERY elegantly for us. If you take someone down to zero HP (or SP), you decide what happens to them. Often this is just used to decide “Dead or Unconscious”, but it’s a MUCH more powerful tool than that. The guy who takes his last HP could decide his enemy listened to reason and surrendered. , just as the guy who takes the last SP could decide he distracted the guy enough for him to get stabbed (or that he had just gotten through, just as he got killed, for maximum angst). The limiter on this is not a function of rules, but of what makes sense to the table, as it should be.

3- Important note: In all three cases, the activity moves towards action. That is, just studying something isn’t going to make progress against a challenge (unless studying IS the challenge) – the knowledge needs to be gained and applied. This need not be _strictly_ applied with each roll, but it must be part of the trend. That is, if you sneak past the guard and get him to down to zero, you should be taking him out (in whatever manner you see fit). If all you’re doing is going past him and not actually impacting the situation, that’s just a roll, not a challenge.

What are hit points?

Historically, they were a measure of health and toughness, but over time (much like armor class) that got more and more abstracted until you’re left with some incongruous trappings (like tying them to constitution) and a simple reality: They’re a pacing mechanism. They measure how long something stays fighting, which in turn is a yardstick for scene length. If you need evidence of it, look at how monsters were changed with Monster Manual 3 – the change to hit points was not because monsters had somehow been written up as too healthy, it was to address pacing issues.

In fact, you could probably get away with really simplifying hit points by just tracking the number of “hits” a monster took over the course of a fight. Hit him with a basic attack or an at will, or do some real on going damage, it’s one hit. Hit him with an encounter power and it’s two hits. Daily and it’s 3. Strikers by and large do an extra hit. Simple, yes, but such a fight would be virtually identical to a normal one from a player’s perspective (barring some sort of math nerd tracking all damage at all times) provided the number of hits worked out close to those of a regular fight. Players would still track damage (because, hey, they have the bandwidth) but the GM could more easily tune fights up and down with this system.[1]

The problem is that players wouldn’t stand for it. We _like_ rolling damage. One of the most established truths of D&D is that the roll to hit and the roll for damage are separate things. “Margin of Success” is one of those idea that may find root in other games, but which has no home in D&D. There are crits, and that is good, and one or two feats that can bleed across a little, but by and large the damage dice are beholden to none. A great hit can roll crappy damage, or a minor attack can max out. It’s just one of those things that makes it D&D.

And that’s the inversion I think we need. The instinct is to expand the scope of skill challenges, taking advantage of their structure because it’s intellectually exciting, but I think that’s too far removed from what excites people about D&D. We want to hit things with axes and roll for damage: Why not solve all our problems that way?

Which is to say, my not literally give challenges hit points, and let skill rolls do damage?

It sounds crazy on the surface, I know, but it’s actually a surprisingly workable model. Obviously you’ll have to call it something other than Hit Points – Challenge Points abbreviates to CP, which is already in use, so let’s say Situation Points, or SP – and damage might be called something like “Progress” but we all know a damage roll when we see it.

So that guard over there? He’s a 20 point challenge. Every time you beat him with stealth, you inflict damage (sorry, ‘make progress’) on those points. Say a simple rule of thumb: Untrained skills do d6 + Stat + 1/2 level damage. Trained do d8, trained plus skill focus does d10. Easy peasy. Your stealth guy is gonna chew up that challenge in no time, but if he fails, the guard goes active, but his hit points are still based on the remaining SP (which additionally allows for the small, skirmishy fights we were talking about). That’s one example, but it’s easy to see others, with skill use being freely interchangeable with actual attacks when appropriate, it becomes easy to think of the difficulty of skill checks as a defense: you don’t just roll to avoid the storm, you roll to kicks its ass (which is to say, to maintain control of the situation. Players may not _be_ more proactive in these situations, but they’ll like feel like they are.

Obviously, this requires a pretty drastic reconsideration of how these encounters are built and budgeted, but I am confident it can be done, and more, it can be done in a manner that continues to stay within the rules and spirit of 4e. More on that tomorrow.[2]

1- In doing so, the GM would effectively have just turned fights into skill challenges. The “hits” model is essential the same at its heart.

2- Unless I get totally sidetracked by my inspiration of how to make Hawkman awesome.

This all began with @sarahdarkmagic raising an innocuous question on twitter: how to run breaking into a castle in 4e. Specifically, the issue was that doing it as a skill challenge did not provide the right feel, which was more fast and skirmishy, taking out guards and such. Now, I could argue that a skill challenge can be made to do that, but I’ll concede it’s hard. Making skill challenges feel dynamic is a trick of its own, and not an easy one to master. When you add in combat, this complicates things even further, since 4e’s world of skills and the world of fighting are very far apart indeed.

A number of very good suggestions were put forward, including the incorporation of daily and encounter powers into skill challenges for bonuses (always a good practice) but that got me thinking about the nature of this specific problem and how I’d want it to go as a player. I’d be thinking in terms of stealth computer games like Thief or Splinter Cell, where play is like a montage of badassness. You sneak up on a guard, find some clever way around the complication, then take him out.

In practical terms, that’s an encounter in miniature – opposition + some interesting twist. And right off the bat, this reveals a lot of what makes this hard for a GM. While this mini-encounter may have fewer moving parts than a big one, it’s still a pain to design. The real work in encounter design is not filling in the details, it’s coming up with the hook that makes this encounter stand out. Coming up with a sequence of those would be work enough, and having to do it for a single skill-challenge equivalent (centered around one player no less!) is way too much work for the payout[1].

So you need to cut corners. Trim down the number of encounters. Maybe re-use some tricks. And then you bump up against the other problem, how to actually run it. Yes, you could make it purely skill driven, but the reality is our player wants to stab himself some guards (or snap their necks or something equally dramatic). That demands fast, brutal fights. No problem! Sounds like a job for Minions, right?

Well, no. The problem is that if you use minions, the guards are no longer a credible threat. Why bother to be stealthy when you can kill these guys with a forcefully thrown piece of paper? But if you make them full-on opponents, then this whole thing is just going to drag out impossibly long. You might think you could make do with lower level opponents, but even a level 1 enemy can have 20-odd hit points, and it’s easy for that to be the wrong number[2], to say nothing of the lameness of using weenie opponents like that.

So we need some way to tune the enemies more finely than they currently, and that’s what got me thinking that maybe we have the problem backwards. And that’s where I’m going next.

1 – Unless you also play stealth video games, and have a mental library of situations to steal and reskin. If so, awesome.

2 – That said, here’s a dirty trick that works only for rogues with daggers or shuriken. Their actual weapon damage is pretty trivial, quickly overcome by their bonuses and sneak attack bonuses. For them, figure out their minimum damage on an attack (all bonuses +1 for a 1 on the roll) and add 4 to that. That’s your perfect HP number. That opponent will probably survive the initial attack if it’s not a backstab, but will almost certainly die if it is.