Combat Sans Matrix

Intuitive D&D combat without charts

Our THMod “to-hit” method is based loosely on OD&D’s unofficial THAC0 (To Hit Armour Class 0) system. However, we’ve managed to remove much of the math from even that easy-to-use rule modification. In conjunction with our revised armour class guidelines, our THMod system ensures that you’ll never have to consult a combat matrix again.

THMod Basics

Our THMod “to-hit” system works by providing a collection of cumulative “to-hit” modifiers. The sum of these modifiers is added to a combatant’s normal 1d20 “to-hit” roll; if the modified roll is equal to or greater than the defender’s armour class, the attack is successful and damage may be rolled.

THMod Modifiers (General)

The following THMod modifiers apply to all combat situations:

Condition Modifier Condition Modifier
Weapon Mastery: UN -2 Attacker Exhausted -2
Weapon Mastery: BA 0 Target Exhausted +2
Weapon Mastery: SK +2 Total Darkness -4
Weapon Mastery: EX +4 Partial Darkness -2
Weapon Mastery: MS +6 Missile Range: Pt. Blank +1
Weapon Mastery: GM +8 Missile Range: Short 0
Attack from Behind +2 Missile Range: Medium -1
Attack from Above +1 Missile Range: Long -3

THMod Modifiers by Class and Level

Use the following THMod modifiers to reflect combatant skill by class and level; note that values are based on the existing OD&D combat matrices (RC/106-7):

Magic-User Level Cleric/Thief Level Fighter Level THMod
1–5 1–4 1–3 +1
6–10 5–8 4–6 +3
11–15 9–12 7–9 +5
16–20 13–16 10–12 +7
21–25 17–20 13–15 +9
26–30 21–24 16–18 +11
31–35 25–28 19–21 +13
36 29–32 22–24 +15
33–35 25–27 +17
36 28–30 +18
31–33 +19
34–36 +20

THMod Modifiers by Monster Hit Dice or Attack Rank

Use the following THMod modifiers to reflect monster combatant skill by hit dice; note that values are based on the existing OD&D combat matrices (RC/106-7). While our class system does not make use of demi-human attack ranks, they are provided below for conversion purposes in those campaigns where they do apply.

Monster Hit Dice Attack Rank THMod Monster Hit Dice Attack Rank THMod
Normal Man 0 13+ to 15 H +12
Up to 1 (inclusive) +1 15+ to 17 I +13
1+ to 2 +2 17+ to 19 J +14
2+ to 3 +3 19+ to 21 K +15
3+ to 4 +4 21+ to 23 L +16
4+ to 5 A +5 23+ to 25 M +17
5+ to 6 B +6 25+ to 27 +18
6+ to 7 C +7 27+ to 29 +18
7+ to 8 D +8 29+ to 31 +18
8+ to 9 E +9 31+ to 33 +19
9+ to 11 F +10 33+ to 35 +19
11+ to 13 G +11 35+ and up +20

THMod Modifiers in Combat

During an attack, the player or DM need simply apply all relevant THMod modifiers to the standard 1d20 “to-hit” roll. If the modified “to-hit” roll is equal to or greater than the defender’s AC, the attack is successful.For convenience and easy look-ups, we recommend that a combatant’s THMod with each weapon or attack type be noted on the character sheet or NPC/monster description. Below are some examples, using the data above:

Pyrohydra with 11 hit dice, attacking from above: THMod = +11 [+10 (HD 11) +1 (attack from above) = +11]
4th-level fighter with Skilled mastery with the sword: THMod = +5 [+3 (4th-level fighter) +2 (Skilled mastery) = +5]
4th-level fighter, as above, attacking from behind in total darkness: THMod = +3 [+3 (4th-level fighter) +2 (Skilled mastery) +2 (attack from behind) -4 (total darkness)]
Goblin warrior unskilled with the spear: THMod = -1 [+1 (HD 1-1) -2 (Unskilled mastery) = -1]
2nd-level thief with DEX 16 and Basic mastery of the long bow, firing a short range: THMod = +3 [+1 (2nd-level thief) +2 (DEX adj.) +0 (Basic mastery) +0 (short range) = +3]
2nd-level thief, as above, firing an arrow +1: THMod = +4 [+1 (2nd-level thief) +2 (DEX adj.) +0 (Basic mastery) +0 (short range) +1 (arrow +1) = +4]

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Erin Smale

Erin Smale is the author of the Chimera RPG and WelshPiper.com, a sporadic, rambling blog that provides tips and tools for the time-challenged game master. He lives in secret along the New Jersey coast with his ass-kicking wife Kim and astoundingly cute dog Bella.

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