Two Against Darkness - The Madness

03 Feb, 2025

Last time I presented a method to run B/X adventures for two D&D4 characters. Now I'll meditate about the differences in math and philosophy between B/X and D&D4, show you how I got the numbers I did and how to extend them into higher levels.

D&Ds Core Assumption

All versions of D&D use Hit Points as an abstraction for injury. In real life, if you're shot by a gun there's a chance you'll die. Go figure right? But there's also a chance you'd get winded, or hamstrung, or knocked on your ass by that bullet. D&D abstracts away all of those possibilities and leaves only the chance of death (or left dying in D&D4's case). If you're shot a second time, you're more likely to die right? D&D represents that "closeness to death" through Hit Points. Each attack that hits deals some damage to you, reducing your hit points. When you reach 0, you die (or are dying).

The difference between old D&D and D&D4 are in how much you ought to be able to take.

OD&D was so generous you know. In Chainmail, if you got hit you died! Poor foot soldier. But you're special adventurer! You have one Hit Dice! You roll it to determine your HP. When you're struck, your attacker rolls their weapon's damage die and deals that much damage. That means now you have a chance of surviving a hit! You're not just dead instantly! Isn't that great? With levels of experience, you'll get more hit dice. With each hit die, that's another hit you have a chance to survive. A 2HD Fighter may survive two hits and can almost certainly survive one. A 3HD Fighter may survive three hits and can likely survive two. A 4HD Fighter may survive four hits and can certainly survive at least two at this point. So it begins as a chance for survival, a saving throw. Then it becomes a resource. The hit die for Fighters and Monsters in B/X is a d8 or 4.5 hit points per die. This lines up virtually one to one with damage dice, though most weapon dice are smaller d6s.

D&D4 on the other hand has plans. This is a game that wants to be about moment to moment action. You have sweet powers that let you do that after all. So the designers asked themselves, "How many hits should you take before you go down?" and decided that four hits was the number.¹ A pretty typical attack in D&D4 deals 1d8+4 or 8 damage so a 1st level monster has 32 hit points. PCs have fewer hit points, but they have healing and second wind, stuff that monsters almost never get. Each level, they gain 1HD. Monsters have a HD of 8 while the average PC has a HD of 5 (very close to the fighters of yore). Damage should scale to match HP to largely preserve this balance. PCs get powers and feats, Monsters just increase their damage by their level. Whether or not PCs actually make the +2 damage per hit per level to keep up is a matter of debate for another time.

So to bridge these two sets of assumptions: A D&D4 PC can survive about 4 hits on average. Doesn't that make them 4HD? And each level they gain gets them another 5 HP, or 1 HD.

The Madness

D&D4 introduced minions, elites, and solo monsters which are incredibly useful here. A minion can survive only 1 hit, so it's 1/4 of a normal monster. An elite has double health, so it's 2x a normal monster. A solo monster has quadruple health, so it's 4x a normal monster.

Armed with knowing our PC's HD rating, we can create a scale relative to the PCs that tells us how much HP and damage a monster deals based on their HD. If its a 1/4 of their HD, that's a minion. If it's about double, that's an elite. If its about quadruple, it's a solo. Right?

Well there were two early problems. First, HD doesn't go like that high you know. I want solo monsters to happen because they're a huge threat to just two PCs. So I decided I wanted the Mob, Monster, and Elite HD bands to be the same size, ideally 3. This should maximize monster type diversity. I'll start the Monster band at exactly the PC's HD to be generous. There wasn't enough room at level 1 for the Mob band to be size 3, so its size 2. And that's how Level 1 was generated!

Second, what do we do with monsters that are half the PCs HD? The drop from full monster to minion is a little sharp. If I had to pick, I'd err on the side of minion for the epic feel, but I think you'd lose a lot of good monsters that way. That's where the mob comes in, a sort of half monster that doesn't exist in D&D4. It's quite useful here in a way that becomes obvious by skimming through B/X adventures.

We can use the famous MM3 on a Business Card to generate numbers for the monsters. Then we can make an index card with the stats for Minions, Mobs, Monsters, Elites, and Solos with HD ranges for which goes where. A nice thing about D&D4 is attack bonuses and defenses are consistent by level, we don't need to write another thing down.

Higher Levels

We'll start with HD. To preserve our heuristics, the first thing we need to do for level 2 is increase the Mob band to size 3 like we wanted to. Then we'll just increase the bands by 1 every level like so:

This makes sure there are still relevant threats as high level as possible. It's important to remember that for Two Against Darkness, Solo threats are basically impossible to fight fairly.

For HP, I use the 24 + 8 • level formula to generate Monster HP, then just halve, double, and quadruple that to get Mob, Elite, and Solo HP respectively. Minion HP is always 1!

Next, damage. MM3 on a business card shows you that damage increases by 1 per level. It doesn't tell you that elite damage is about 50% more than regular monster damage and solo damage is double elite damage. Since I made up mobs, it doesn't tell you about those either! I decided they dealt about 25% less damage which is the same as reducing the die size by one. Take note here: because of the way I've maxed out the damage dice, reducing or increasing the die size really does change it by about 25%, very useful for aoe attacks, special attacks, or if you want to add the Brute monster role.

I decided to maximize the number of damage dice. The reason I did this was so many B/X monsters have multi attacks so if you can simply roll half the dice on each attack the problem solves itself! It also has the effect of increasing or decreasing the die size changes by 25% as I mentioned above. The second note, as we level we should try to keep the number of dice for Monsters even. That way we can evenly increase the number of dice by 50% for elites and halve the number of dice for minions.

I give an average value for use at the table, I hate rolling for damage personally! I use the average value all the time.

That's the difficult part, the rest is easy. Attack bonuses increase by 1 per level. Defenses increase by 1 per level. And for DCs, look them up on the Difficulty Class By Level chart:

Level 2

Let's go through the process for level 2.

First the top line. We can just look up the DCs, they're 9/13/20 for this level.

Next, attack bonuses and defenses. Let's look at the card: ![[mm3businessfront.gif]] Our hit bonus is now +7. As stated before, it'll be 2 less for +5 against Non Armor Defenses (NADs for short). They'll have AC 16 and NADs of 14.

Next our HD ranges. Our heroes are 5HD now. We went over the process of making the ranges above: 1 or less HD are minions, 2-4 HD are mobs, 5-8 HD are monsters, 9-11 HD are elites, 12 or more HD are solos.

Now we'll figure out how much HP each category has. Looking at the card, skirmishers are normal monsters for HP, we'll have 24 + 8•2 HP so 40 HP. Mobs are half so 20. Elites are double so 80. Solos are quadruple so 160. Minions are always 1 HP like Chainmail foot soldiers.

Next, damage. Monsters should be dealing 10 damage on a hit. Turning that to dice I got 2d8+1. Reduce the die size for mobs, that's 2d6+1. Halve the dice for minions, that's 1d8+1. Add an extra die for elites, that's 3d8+1. Double elite damage for solos, that's 6d8+2.

And with that, we're done! I'll also show you the card for level 3, these three cards are likely all the cards you'll really need. But if you do go further beyond, you'll know how to make them.