Sunday, February 19, 2012

Combat Rules I: the Basics

Philosophically, I regard combat as a complication in the exploration/treasure-hunting game that is D&D. Monster encounters are a risk that can totally derail an expedition, or use up valuable resources (spells, arrows, flasks, hit points, etc), not to mention eating up table-time (of particular importance with my Black Fog rules in play). The party is awarded XP for these encounters as a kind of consolation prize for the resources, or as a reward for good tactics & strategies that allow them to overcome the encounter at little or no cost.

The way that combat itself plays out has been fine-tuned over the years as I increase my understanding of what works for me and what my players enjoy. We have a thorough mix of Combat as Sport vs Combat as War perspectives, so I've tried to aim toward a middle-ground. My players like to meet monsters head-on, but they have also learned not to rely too much on luck or statistics to keep them on their feet.

The combat mechanics start from the Swords & Wizardry: Whitebox rules. Many of my alterations are inspired by the various editions of Basic D&D, from B/X through RC, with borrowings also from AD&D 1st edition and of course the OSR. A number of terms have been renamed either to guide interpretation of the mechanic, or to borrow terminology familiar to my players (so a number of terms have been borrowed from Warhammer 40,000 and Magic: the Gather, for example).

Mechanical Overview

The Partholon campaign uses ascending Armor Class. My calculations differ from those used by S&W, so that an unarmored character is AC 10, and the descending AC 0 is converted to AC 20. Similarly, my calculation of combat modifiers differ slightly, so that a level 1 PC starts with an attack bonus of +1. I do not use variable weapon damage, so all attacks deal d6 damage, and I don't normally use multiple attacks for monsters or for PCs. If a monster attacks twice in a round, that's a special ability.

A natural 20 always penetrates armor, a natural 1 always fails. I don't normally include critical hits or fumbles, but circumstances may call for similar outcomes - such as when a PC attempts some inspired stunt and the dice just hate him.

Time & Movement

A combat round is roughly 10 seconds of game time. A character or monster may move at Encounter speed and still take an action, or run at Explore speed without taking any other action. 

AP vs AC

Attack modifiers are termed AP, which stands for either Attack Power or Armor Penetration. AP is based off of class & level primarily. Dexterity modifies Ranged AP, and Strength modifies Melee AP only when a heavy weapon is being used.

If AP equals or exceeds AC, a wound is scored for 1d6 hp. A PC with HD 4 or better deals the best of 2d6, while a PC with HD 8 or better deals the best of 3d6 damage. A monster with HD 5 or better deals a full 2d6 damage, while a monster with HD 10 or better deals a full 3d6 damage. Monsters with these improved damage ratings may be able to split their attacks among multiple targets, rolling AP vs AC for each target and dealing a single d6 to each.

A damage result that is no more than the target's HD is very minor, suggesting the fatigue of fending off deadly strikes and the dull aches of repeated blows foiled by armor. Of course, this damage adds up, and an exhausted combatant may be unable to mount any meaningful defense. Being nickled and dimed to 0 hp is every bit as dangerous as being dropped by a few brutal hits.

In the course of a round, each combatant is understood to be making several physical attacks against an opponent, as well as parrying and evading incoming attacks. The combat roll abstracts the progress of the entire round to simplify the whole process. Rather than testing attack skill versus defensive skill, and then testing to see whether any damage penetrates armor, D&D checks first whether any damage is scored, and then interprets the damage roll to indicate the relative skill of attack and defensive routines in the process.


When reduced to 0 hp, the PC is not automatically slain. He collapses unconscious and must roll a d6 to determine his status. On a 1 or 2, he is revived after combat ends, but suffers a hampering injury for 2d6 days. On a 4-6, his wounds are more serious and may prove fatal. A roll of 3 is treated as a 1-2 result if he was wearing a helmet, in which case the helm is ruined but his life is surely saved. Without the helm, a roll of 3 is treated as a 4-6 result.

In the case of serious wounds, the PC will not revive after combat ends. The following turn, if he is not revived by magic, he may roll a d6 again. On a 1, he recovers on his own. On a 6, he succumbs to his wounds and dies. On a 2-5, her remains unconscious and must roll again the following turn. In any case, when and if he recovers from this state, he suffers a hampering injury for 2d6 weeks.

If a PC is already injured and receives the same injury again, the effect is extended. If the existing injury has less than two weeks remaining to heal, a repeat of short-term injury is upgraded to long-term. If the existing injury is long-term, compounding the injury makes it permanent. Adding a long-term injury onto a short term injury is a special case: roll a Save with a Con modifier. On a failure, the injury is permanent. On a save, the injury's duration is extended to 3d6 weeks.

Hampering Injuries
1 Arm rendered useless* Cannot put the afflicted arm to use.
2 Eye damaged* -2 Ranged, or blinded if both eyes have become injured
3 Leg impaired* Reduce speed by one level
4 Hideous scars -1 to Reaction rolls, Command, and Leadership
5 Enfeebled (broken ribs or similar) -2 AP, AC, & Carrying capacity, and run at x2 rather than x3
6 Skull-cracked Must roll Int or Wis to cast spells and becomes Berserker**

*In the case of arm, eye, and leg injuries, roll even/odds to determine left/right.
**Berserker characters become irrationally violent during combat. Must roll Wisdom to resist plunging into melee when combat begins, and must similarly roll Wisdom to withdraw or retreat from melee. While in melee, the character gets +2 AP and -2 AC.

I like my players to have some investment in their characters, rather than treating PCs as pawns to play with and discard during the game. At the same time, I want to give players a strong incentive to play smart and retreat from a fight that is going badly. So far I find this injury system serves both goals well.

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