Dark Sun THAC0 & Initiative Calculator

Initiative Tracking

Add Combatants

Enter the total for this round (d10 roll + weapon speed, spell time, or other action modifier)

Current Round: 1

Current Segment: -

Add combatants and start combat to see the initiative order.

Combat Log

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THAC0 Calculator

Attacker Information

Hit Probability: +0
Damage Adjustment: +0
Note: Only applies to ranged weapon attacks

Combat Modifiers

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Initiative Calculator

Character Information

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Action Information

*Foreign environment refers to situations like underwater combat for land creatures, etc.
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Damage Calculator

Weapon Information

Damage Modifiers

Select a weapon to see damage information

Reference Tables

Situational Modifiers

Situation Modifier
Attacker on higher ground +1
Defender invisible -4
Defender off-balance +2
Defender sleeping or held Automatic hit
Defender stunned or prone +4
Defender surprised +1
Missile fire, long range -5
Missile fire, medium range -2
Rear attack +2

Weapon Material Modifiers

Material Cost Weight To Hit Damage
Steel 100% 100% — —
Bronze or agafari 50% 100%/50% -1 —
Bone or chitin 5% 50% -1 -1
Stone or obsidian 3% 75% -2 -1
Wood 1% 50% -3 -2

Action Modifiers

Specific Situation Modifier
Attacking with weapon Weapon speed
Breath weapon +1
Casting a spell Casting time
Innate spell ability +3

Magical Items

Item Type Modifier
Miscellaneous Magic +3
Potion +4
Ring +3
Rod +1
Scroll Casting time of spell
Staff +2
Wand +3

Monster Size (for natural weapons)

Size Modifier
Tiny 0
Small +3
Medium +3
Large +6
Huge +9
Gargantuan +12

Standard Modifiers to Initiative

Specific Situation Modifier
Hasted −2
Slowed +2
On higher ground −1
Set to receive a charge −2
Charging −1
Wading or slippery footing +2
Wading in deep water +4
Foreign environment* +6
Hindered (tangled, climbing, held) +3
Waiting +1

Dexterity Score Effects

Score Reaction/Init. Adj. Missile Attack Adj. Defense Adj.
1 -6 -6 +5
2 -4 -4 +5
3 -3 -3 +4
4 -2 -2 +3
5 -1 -1 +2
6 0 0 +1
7-14 0 0 0
15 0 0 -1
16 +1 +1 -2
17 +2 +2 -3
18 +2 +3 -4
19 +3 +3 -4
20 +3 +3 -4
21 +4 +4 -5
22 +4 +4 -5
23 +4 +4 -6
24 +5 +5 -6
25 +5 +5 -7

Strength Score Effects

Score Hit Prob. Dam. Adjust.
1 -5 -4
2 -3 -2
3 -3 -1
4-5 -2 -1
6-7 -1 0
8-9 0 0
10-11 0 0
12-13 0 0
14-15 0 0
16 0 +1
17 +1 +1
18 +1 +2
18/01-50 +1 +3
18/51-75 +2 +3
18/76-90 +2 +4
18/91-99 +2 +5
18/00 +3 +6
19 +3 +7
20 +3 +8
21 +4 +9
22 +4 +10
23 +5 +11
24 +6 +12
25 +7 +14

Melee Weapons

Weapon Speed
Dagger 2
Short sword 3
Long sword 5
Two-handed sword 10
Battle axe 7
Great axe 9
Club 4
Mace 7
Spear 6
Pike 13

Ranged Weapons

Weapon Speed
Short bow 7
Long bow 8
Light crossbow 7
Heavy crossbow 10
Sling 6
Dart 2
Javelin 4

Terrain Effects Table

Terrain Initiative Modifier Caster Level Modifier Defiling Radius
Barren (boulder fields, sandy wastes, salt flats, silt) +4 –2 10 feet/spell level
Infertile (stony barrens, rocky badlands, bare mountains) +2 –1 5 feet/spell level
Fertile (cities, mountains, oases, scrub plains) 0 0 3 feet/spell level
Abundant (mud flats, verdant belts) –2 +1 2 feet/spell level
Lush (forests, gardens) –4 +2 1 foot/spell level

Special Notes

  • Obsidian Plains: No spellcasting possible without defiling or alternative energy sources
  • Defiling: Treat terrain as 2 steps more fertile for effects (minimum lush)
  • Rite of Blood: Treat terrain as 1 step more fertile, +1 caster level bonus, take 1 hp damage per spell level
  • Advanced Defiling: Full round casting, +1 effective caster level or recover expended spell, staggered for spell level rounds after casting
  • Defiled Ground: +2 initiative penalty when casting on previously defiled areas (unless defiling yourself)