Tuesday, March 6, 2012

A Possible Fatigue Rule in Reconceiving Damage

In the past, I have alluded to the fact that I continue tinkering with rules to produce my own version of the ideal OSFRPG, drawing mostly on B/X, Holmes, and Swords & Wizardry, while adding in house rules I've used over the years, my own new ideas (wand spells!), and anything cool and relatively rules-lite from any OGL source I might find helpful or adaptable, including Pathfinder. Usually these rules documents get shared with friends, experimented with, and put away in files against The Day of the Great Integration. But A Paladin in Citadel recently complained about the lack of fatigue rules in D&D, so I was jarred into sharing what I had been working on, below.

Hit Points (HP) are an overall measure of how long one can stand up to the demands of combat. When your character reaches 0 hit points, your PC is exhausted. Exhausted characters (1) lose their Dexterity bonus to armor class, (2) begin taking Constitution damage, and (3) have to make a Con check at the beginning of each round to successfully act.

At 0 HP, the character may choose to continue the strife or retreat, but any additional damage taken will come directly off of the PC's Constitution score. On every round after reaching 0 HP, the player must roll a Constitution check. Let's say the player Cassie is playing her character Bork the Barbarian, Fighter 3. In combat, Bork reaches 0 HP and has a phenomenal Con of 18. The next round, Cassie rolls a d20 and the result is a 16. Having passed the check, Bork may take only one regular action: move or attack (or cast, if Bork had been a magic-user1). Bork attacks and deals damage to the opponent, but takes 5 points of damage in the ongoing melee, bringing the PC's Con score to 13. Next round, Cassie rolls the check and rolls really low: a 3! Bork continues the fight, but deals no damage. However, the monster deals two points of damage, bringing Bork's Con to 11. Next turn, Cassie rolls the check to see if the Bork can take an action. The roll is 12. This round, heaving from the strain, Bork is unable to successfully accomplish anything due to his exhaustion. (The GM might narrate Bork attempting the intended action something like: “The arc of Bork's great club is so sluggish, the bugbear chief has plenty of time to duck the swing.”) Unfortunately, Bork continues to take damage. This round, he gets smacked for 7 points of damage, bringing the PC's Con down to 4. Rolling a 4 at the beginning of the next round, Cassie decides Bork will get out of the fight while the getting is good! If Cassie had allowed Bork to reach Con 0, he would have died.

For every one hour of rest, the PC gains back the number of HP equal to one's current Con score. If the PC has undergone Con damage, one uses the temporary Con score. To continue our example from above, one hour of healing would get Bork 4 hit points.

Sleeping a solid 8 hours, in a relatively comfortable environment will heal 8 x Con hit points. If Con damage has been suffered, then those eight hours would also heal one lost Con point. So building on the example above, Bork would gain 24 HP back and have a Constitution of 5. However, the maximum number of HP than can be regained must take into account the number of those hit points that were Con bonus. In Bork's case, nine points of the character's original HP total remain out of reach until Con levels are regained that enable the restoration through Natural Healing of bonus HP tied to Con. Fourteen nights of sleep back at the Green Dragon Inn are in order, if they can be had. If the adventure presses and time is precious, the player will weigh the need for Con and HP restoration against the pressure of time and the threat of failure.

First level healing spells (i.e., Cure Light Wounds) heal only hit points and not Con damage. Higher level healing spells heal Con damage first, then any hit points.

1Note, however, the dangerous synergy of Con damage with the desperate Con for casting rule. If a magic-user is out of spells and chooses to cast a known spell from a spell-book by sacrificing Constitution points (one point per spell level), the magic-user can die very quickly.


  1. Interesting concept. I like the idea of fatigue begetting more fatigue. Fatigue extends the ability of the character to continue fighting after reaching 0 HP. That gives the player the opportunity to play the hero and continue fighting while close to death or make a retreat. However, it eliminates the unconscious condition correct? Also, is the DC for the con check 10? It would be interesting to see how character builds adapt to this concept, i.e. go for higher con scores.

    Finally, would it complicate things too much to extend the fatigue concept into positive HP realm? I.e fatigue begins affecting the ability to attack or make your character more prone to future damage as the damage taken increases. I suspect a larger HP pool would need to be created in order to implement this concept.

    I always found the construct that you fight like you are at full health through the entire combat up until the point you drop to zero and then suddenly you stop very jarring.

  2. Thanks, Trin.

    The DC, if you will, is whatever one's Con is at the time one rolls. This is a low roll check, so, the DC would =/<10 only if your Con score was 10 at the time you rolled the check.

    Your point about falling unconscious is well taken. I'd be tempted to further rule that 0 is "unconscious, dying." You could then continue to lose one point every round, until you reach the negative of your original constitution. So Bork would be Unconscious, Dying each round until he hit -18. Alternatively, people who didn't like the regularity of this could roll dice to see how much a character bleeds out each round until they hit the negative of their Con score and then die.

    I think I like keeping with the original Con/HP breakdown for the fatigue threshold. It makes a kind of logical sense with Con in my mind, and it gives a balance for the dump-stating player, as well as an incentive for improving one's Con at some point.

  3. I see now where my thinking on the constitution check was wrong. I was thinking that a D20 roll higher than the con score was a success for the PC. It is the opposite. A steadily dropping con score does increase the risk nicely.

    The negative con score concept for dying is a nice way of implementing the larger HP pool that I mentioned above. So the four phases a character goes through when damaged are

    Phase 1: N HP to 0 : Non debilitating wounds
    Phase 2: HP = 0, Con to 0 : Damage crosses the threshold the PC can withstand and becomes debilitating
    Phase 3: HP = 0, Con 0 - (-Con Score + 1): Unconscious, dying
    Phase 4: Con <= (-Con): Death

    A PC's total HP pool than will be N HP + 2 x CON

    It will make for an epic story when the hero begins the accelerated slide toward death only to vanquish the villain just before taking what may be his final breath.

    Very nice fatigue rule.

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  6. I like the idea, but don't like the idea of (re-)introducing the roll low. "Higher is better" is one of the best things that d20 brought to the game, IMO (along with the 'unified' d20 mechanic).

    Since this is a Con check, we just need to set a DC to an appropriate level, and make Con checks against it.

    Since the DC is supposed to 'slide', what should it be? 20 - Con.

    Roll Low Success chance for Con = 5 is 25%, when Con = 10 is 50%, Con = 15 is 75% and so on, so we want our DC to map closely to that.

    When Con = 5, the bonus RAW is -3, When Con = 10, the bonus RAW is 0, and When Con = 15, the bonus RAW is +2,

    To succeed on a d20 skill check 75% of the time, you need a 6 or better.
    To succeed on a d20 skill check 50% of the time, you need a 11 or better.
    To succeed on a d20 skill check 25% of the time, you need a 16 or better.

    So, Con 15 rolls DC20-15=DC5, d20+2, effective DC is 3 (slightly easier)
    So, Con 10 rolls DC20-10=DC10, d20+0, effective DC is 10 (the same)
    So, Con 5 rolls DC20-5=DC15, d20-3, effective DC is 18 (slightly harder)

    If a roll of 20 automatically succeeds, then, even a CON of 1 or 2 can still pass.

    Just a thought.