Rolling The Hit Dice
Some ways to use HD as a resource
RPGDESIGN
10/6/20264 min read
Design begets design. Reading about Montante Hack and a linked post about The Hit Dice Wounds System inspired me to come up with ways to use the Hit Dice more. (To be clear, by HD we mean in the D&D sense: your character grows more resilient with experience, getting more hit points and this increase is determined by your Hit Dice that you roll at each level.)
Here's a key observation: if we talk about rolling dice, amount of which is increasing at each level, then we slowly move away from (modern) D&D paradigm to get closer to a dice pool system. With that out of the way, let's have a rapid-fire look at tools we can utilize.
Hit Dice As A Pool
Currently, Hit Dice represent/abstract hits our characters can take. We can change the equation and additionally use them to represent hits our characters can dish. With this method, simply gather your HD pool and distribute it amongst your targets, then roll to determine success. Some things to consider:
Variable or Fixed Hit Dice
These days different D&D classes have different HD because we as players do have access to different types of dice. Back when there was only d6s, there was an alternative approach: classes gained HD at different rates.
Different Weapons
Do we want multiple weapon categories with respect to damage? In that case, we can change "success" threshold based on weapon. E.g. on a pool of d6s, light weapons deal damage on 6s, while 2-handed weapons deal on 4-6. Also, if we have variable HD classes, then dice size-threshold interactions can become class features like "thieves (d4 HD) can only use light weapons, which normally deal damage only on 4, but with sneak attack they deal damage on 2-4."
Opponent Defense
Do we want to differentiate opponents with respect to defenses? Maybe we don't go for a "roll over threshold" but instead a "roll between upper (determined by weapon) and lower (determined by opponent's defense) boundaries". Maybe opponent defense lowers your dice pool, or (a stronger version) ignores certain amount of successes.
What Does Damage Mean?
We may remove HD's "ability to withstand damage" aspect and give everyone fixed (let's say 6) hits. With this method, high level fights get shorter, not longer.
We may keep HD as is, and each damage sustained becomes a strike against your (increasing with level) HD. However, if we use variable HD by class, we'd need to differentiate between d4s and d10s, and end up back at hit points.
If we're feeling cruel, we can introduce a death-spiral where each damage reduces your HD pool. This may make intuitive sense (it is called Hit Dice, after all) but death spirals generally favour first strikers, so keep that in mind.
Back To D&D (5E): Hit Dice As A Resource
If we don't want to stray too far from D&D-likes, then we hit a couple of walls. We cannot use regularly roll HD for offensive purposes because there are already systems in place for that (like Base Attack Bonus, Proficiency or what have you). Similarly, we cannot roll HD for defensive purposes because we have hit points and we don't want to double count. So, if we cannot roll regularly, maybe we should roll and/or spend HD sporadically?
Back in 2003, Eberron Campaign Setting gave characters action points by default. (In retrospect, this must have been a rule from a Dragon article, else WotC wouldn't release it under OGL in Unearthed Arcana (2004).) The most basic benefit that we'll focus for now was this: roll one or more d6 to add to your d20 result.
We can directly map this idea to Hit Dice: "You have a number of HD. Spend one to gain that amount as a bonus." Now let's build upon that idea.
Interacting With 5e's Short Rest
In D&D 5e you can already spend HD to heal. This rule can interact with it: there is only one pool and you can spend HD either to heal or gain bonuses. However, in my view this punishes martials who are expected to take damage and to roll a lot of dice to be effective in combat so I'd advise against it.
I could also suggest "spend HD to regain hit points in combat" but I don't want to hear jokes about "reinventing 4e" so I'll refrain.
Working Within Bounded Accuracy
I'm more than okay with martial characters gaining higher bonuses due to bigger HD. However, a couple of issues come to mind. First, modern D&D wants d20 to be the deciding factor, at least claims so. In such an environment a d10 bonus can be too much. Second, in such an environment you're unlikely to need very high bonuses, so rolling an 8 on your d10 when you needed just 2 can be a little frustrating. So two alternative approaches come to mind.
Bonus as a resource: instead of rolling a single HD to add to a single roll of d20, we can treat result of rolled HD as our total "bonus pool." If you rolled an 8 and needed just 2, you can spend that and have 6 remaining bonus to spend on future rolls.
HD bonus as proficiency: an alternative rule is rolling d(2N) instead of taking +N proficiency bonus. Combining this idea with rollable HD, we can just remove proficiency as a concept from the game. Instead, you roll only with your abilities by default. Classes not only give HD but also grant ways to spend it: wizards can add d6 to their spell damage, rogues can add d8 to their skills, fighters can add d10 to their attack roll or damage and so on. This is not without precedent: just recently Daggerheart tied "skill" bonuses to a resource.
(Of course this would give us a new game that emphasizes ability scores but I think D&D could benefit from picking either abilities or proficiency and focusing on that. Current system has a weird tension between the two and it diminishes the gameplay experience.)
Concluding...
To reiterate: this was just a thought experiment. We can find even more potential ways to use HD if needed. Also there's no study of potential balance issues beyond cursory notes. As we say in the business, "proof is left as an exercise to the reader". I'd also like to mention Crimson Blades 2e as a big inspiration for "hit dice as dice pool" idea.