Combat system

This article is a work in progress!

For an explanation of basic combat for new players, see A beginner's guide to combat.

Attack Roll

Attack Rolls, or AS/DS Checks, are the most common form of combat resolution in GemStone IV.

AS/DS Check

A typical attack roll looks like this:

You swing with a fist-scythe at a lesser orc!
AS: +109 vs DS: +44 with AvD: +39 + d100 roll: +70 = +174
  ... and hit for 20 points of damage!
  Wild slash scratches the back of the lesser orc's hand.
Roundtime: 5 sec.

In an attack roll, the attacker's Attack Strength (AS) is compared against the defender's Defensive Strength (DS), plus an Attack versus Defense (AvD) value based on the weapon type and the defender's armor. Finally, a random number from 1 to 100 (d100) is added to the result. If the final result is greater than 100, the attack is successful. The higher the result is, the more damaging the attack will generally be.

Attack Strength

Attack Strength is a measure of how hard a character or creature is hitting. It is a factor used when calculating the damage caused by physical attacks and bolt spells. It is increased by weapon skill (or spell aiming skill for bolt spell attacks), the weapon's bonus, stat bonuses (strength or dexterity, depending on the kind of attack), combat maneuvers skill, certain spells, and other factors.

Example: With an edged weapon skill bonus of +45, a mithril short sword with an inherent weapon bonus of +5, a strength bonus of +16, and 4 ranks of CM skill providing a bonus of +2 in an offensive stance, the total is: 45 + 5 + 16 + 2 = 68.

Defensive Strength

Defensive Strength determines how well a character or creature is defending against an attack, and is used in calculating the damage taken by physical attacks and bolt spells. It is increased by the presence of a shield and shield skill, the shield's bonus, the amount of weapon skill applied to defense via a particular stance, the armor's bonus, bonuses from evasion/blocking/parrying, Dodging skill, many different spells, and other factors.

Evade-Block-Parry

Even before a character makes a combat roll, it is still possible to avoid attack through one of three secondary means. If a character fails to evade, block, or parry an attack, the various factors involved still contributes to the character's DS when the attack is resolved.

These defenses are passive, so players do not need to enter any commands for them to activate.

You thrust with a spear at a kobold!
The kobold awkwardly scrambles to the right and blocks the attack!

Evade

The odds for an outright evasion are based on the defender's Dodging ranks compared to the attacker's level. It is affected by stats, certain spells, and stance. A character with 1x Dodging training can evade a like-level foe roughly 5% of the time in stance offensive. A character with 3x Dodging training and all other factors the same would have roughly a 15% chance to evade that same attack.

Evade Defense Strength (DS) formula vs melee attacks: $\mathrm {DS} =((\mathrm {BaseValue} \times \mathrm {ArmorHindrance} \times \mathrm {ShieldFactor} )-\mathrm {ShieldSizePenalty} ))\times \mathrm {StanceModifier}$

where

$\mathrm {BaseValue} =\mathrm {DodgingRanks} +\mathrm {AGI} +\lfloor \mathrm {INT} /4\rfloor$ (use Agility/Intuition bonuses, not raw stats)

$\mathrm {ArmorHindrance}$ is 1/2 of the armor's action penalty value

$\mathrm {ShieldFactor} ={\begin{cases}0.78,&{\text{for small shields}}\\0.70,&{\text{for medium shields}}\\0.62,&{\text{for large shields}}\\0.54,&{\text{for tower shields}}\\\end{cases}}$

$\mathrm {ShieldSizePenalty} ={\begin{cases}0,&{\text{for small/medium shields vs. melee}}\\5,&{\text{for large shields vs. melee}}\\10,&{\text{for tower shields vs. melee}}\\\end{cases}}$

$\mathrm {StanceModifier} =75\%+\mathrm {Stance} /4$

Example: In Stance Guarded (Stance = 80), the Dodge DS stance modifier would be 75% + (80/4) = 95%

Spells that improve attempts to Dodge include Mobility, Mass Blur, and Song of Mirrors.

Evade DS bonus is increased by 50% against any ranged attacks (arrows, hurled, bolts), and there is no shield size penalty. It is possible to evade ranged attacks completely, though the chance of a successful evasion is less than the chance against melee attacks.

There is a 1% penalty to dodge DS for each 1% encumbered body weight.

Example: A character with a body weight of 200 lbs. and a defensive stance dodge DS of +100 will sustain a penalty of -1 DS for every 2 lbs. of encumbered weight. With 200 lbs. of encumbered weight, dodge DS will be zero. There is no additional penalty (negative dodge DS) when encumbrance is greater than total body weight.

Block

Blocking is using a shield to intercept an attack. Possessing a larger shield and training significantly in the Shield Use skill can raise the chance of a shield block, along with possessing greater strength and dexterity. Compared to a medium-sized shield, small shields give a -15% chance to block an attack, while large shields give a +15% bonus. Tower shields give a +30% bonus.

The odds for an outright Block are based on the defender's Shield Use ranks compared to the attacker's level. It is affected by stats, shield size, and stance.

A character with 1x shield training and a medium shield will block a like-level foe roughly 5% of the time in stance offensive. A character with 3x shield training and all other factors the same would have roughly a 15% chance to block that same attack.

Shield Defense Strength (DS) formula vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} \times \mathrm {ShieldSizeModifier} \times \mathrm {StanceModifier} \times (2/3)+20+\mathrm {ShieldEnchantBonus}$

where

$\mathrm {BaseValue} =\mathrm {ShieldUseRanks} +\lfloor \mathrm {STR} /4\rfloor +\lfloor \mathrm {DEX} /4\rfloor$ (use Strength/Dexterity bonuses, not raw stats)

$\mathrm {ShieldSizeModifier} ={\begin{cases}0.85,&{\text{for small shields vs. melee}}\\1.00,&{\text{for medium shields vs. melee}}\\1.15,&{\text{for large shields vs. melee}}\\1.30,&{\text{for tower shields vs. melee}}\\\end{cases}}$

$\mathrm {StanceModifier} =50\%+\mathrm {Stance} /2$

Example: In Stance Guarded (Stance = 80), the Shield DS stance modifier would be 50% + (80/2) = 90%

Shield Defense Strength (DS) formula vs. ranged attacks (arrows, hurled weapons, and bolt spells): $\mathrm {DS} =(\mathrm {BaseValue} \times \mathrm {RangedShieldSizeModifier} +\mathrm {ShieldSizeBonus} )\times \mathrm {StanceModifier} \times (2/3)+20+\mathrm {ShieldEnchantBonus}$

where

$\mathrm {RangedShieldSizeModifier} ={\begin{cases}1.20,&{\text{for small shields vs. ranged}}\\1.50,&{\text{for medium shields vs. ranged}}\\1.80,&{\text{for large shields vs. ranged}}\\2.10,&{\text{for tower shields vs. ranged}}\\\end{cases}}$

$\mathrm {ShieldSizeBonus} ={\begin{cases}-8,&{\text{for small shields vs. ranged}}\\0,&{\text{for medium shields vs. ranged}}\\8,&{\text{for large shields vs. ranged}}\\16,&{\text{for tower shields vs. ranged}}\\\end{cases}}$

Parry

Parrying an attack is generally done with a weapon, and can be encouraged through training in that weapon's associated skill or skills. Increased strength and dexterity also contribute to success. Unlike other weapons, using a two-handed weapon increases success chances by 50%. Wielding two weapons at once also increases one's chances.

The odds for an outright parry are based on the defender's weapon ranks compared to the attacker's level. It is affected by stats, certain spells, and stance. A character with 2x weapon training would parry a like-level foe roughly 5% of the time in stance offensive.

One-Handed Weapons

Parry Defense Strength (DS) formula, one-handed weapon vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} _{\mathrm {1H} }\times \mathrm {StanceModifier} _{\mathrm {1H} }+\mathrm {StanceBonus}$

where

$\mathrm {BaseValue} _{\mathrm {1H} }=\mathrm {WeaponRanks} +\lfloor \mathrm {STR} /4\rfloor +\lfloor \mathrm {DEX} /4\rfloor +\mathrm {WeaponEnchantBonus} /2$

$\mathrm {StanceModifier} _{\mathrm {1H} }=20\%+\mathrm {Stance} /2$

$\mathrm {StanceBonus} =\mathrm {Stance} \times 50$

Two-Handed Weapons

Parry Defense Strength (DS) formula, two-handed weapon vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} _{\mathrm {2H} }\times \mathrm {StanceModifier} _{\mathrm {2H} }+\mathrm {StanceBonus}$

where

$\mathrm {BaseValue} _{\mathrm {2H} }=\mathrm {WeaponRanks} +\lfloor \mathrm {STR} /4\rfloor +\lfloor \mathrm {DEX} /4\rfloor +\mathrm {WeaponEnchantBonus}$

$\mathrm {StanceModifier} _{\mathrm {2H} }=30\%+(\mathrm {Stance} \times 75\%)$

Polearms

For polearms gripped with one hand, use the one-handed weapon formula.

Parry Defense Strength (DS) formula, two-handed polearm vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} _{\mathrm {2H} }\times \mathrm {StanceModifier} _{\mathrm {2HPole} }+\mathrm {StanceBonus} +\mathrm {PolearmBonus}$

where

$\mathrm {StanceModifier} _{\mathrm {2HPole} }=27\%+(\mathrm {Stance} \times 67\%)$

$\mathrm {PolearmBonus} =15+(\mathrm {Stance} \times 65)$

Ranged Weapons

Parry Defense Strength (DS) formula, bow vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} \times \mathrm {StanceModifier} +\mathrm {StanceBonus} +\mathrm {BowEnchantBonus}$

where

$\mathrm {BaseValue} =\mathrm {RangedRanks} +\lfloor \mathrm {PerceptionRanks} /2\rfloor +\lfloor \mathrm {AmbushRanks} /2\rfloor$

$\mathrm {StanceModifier} ={\begin{cases}15\%+\mathrm {Stance} \times 30\%,&{\text{for short/composite/long bows}}\\12\%+\mathrm {Stance} \times 25\%,&{\text{for light/heavy crossbows}}\\\end{cases}}$

$\mathrm {StanceBonus} =\mathrm {Stance} \times 50$

Ranged weapon users receive a small amount of DS vs. ranged attacks but the exact formula is not known. There is no stance bonus and only a small fraction of the weapon's enchant bonus is included.

Runestaves

Runestaves are a special defensive weapon handled by spellcasters. They can be swung at an opponent like a quarterstaff, but are not intended for offensive purposes. Runestaves are unique not only in that they can parry magical bolts and ranged weaponry directed at the user, but also that their defensive abilities are derived from how well-trained their holder is in the mystical arts. In the hands of an average warrior or rogue, a runestaff is little more than a pretty stick; when grasped by a talented mage, it can embody formidable defenses.

Any skill in magical arts will give one access to a runestaff's defensive benefits, but a total of 8 ranks of any magic skill per level will provide a defense equivalent to that derived from 1 rank of two-handed weapons skill per level. Higher amounts of magical skill will provide even more defense. There is no theoretical limit to the amount of defense that can be generated in this way.

Skills that contribute to runestaff defense: Arcane Symbols, Harness Power, Magic Item Use, Spell Aiming, Spell Research, Mana Controls, Lores.

Parry Defense Strength (DS) formula, runestaff vs. melee attacks: $\mathrm {DS} =\mathrm {BaseValue} \times \mathrm {StanceModifier} \times 1.5+\mathrm {StanceBonus} +\mathrm {StaffEnchantBonus}$

where

$\mathrm {BaseValue} =\mathrm {ParryRanks} +\lfloor \mathrm {STR} /4\rfloor +\lfloor \mathrm {DEX} /4\rfloor$

$\mathrm {ParryRanks} ={\begin{cases}10+3\times \mathrm {MagicRanks} /20,&{\text{if magic ranks per level }}<4\\10+\mathrm {Level} +(\mathrm {MagicRanks} -8\times \mathrm {Level} )/10,&{\text{if }}4\leq {\text{ magic ranks per level }}\leq 11\\10+(\mathrm {Level} \times (13/10))+(\mathrm {MagicRanks} -(11\times \mathrm {Level} ))/20,&{\text{if magic ranks per level }}>11\\\end{cases}}$

$\mathrm {StanceModifier} =20\%+\mathrm {Stance} /5$

$\mathrm {StanceBonus} =\mathrm {Stance} \times 50$

Parry Defense Strength (DS) formula, runestaff vs. ranged attacks: $\mathrm {DS} =(\mathrm {BaseValue} \times \mathrm {StanceModifier} \times 1.5)/2+\mathrm {StanceBonus} /2+\mathrm {StaffEnchantBonus} /2$

Damage Calculation

Location

If an attack is successful, it deals damage to a random location on the defender's body. Players can AIM or AMBUSH an attack against a specific location, increasing the chance of hitting it, but doing so consistently requires extensive training in the Combat Maneuvers and Ambush skills and is mainly useful for characters above level 20.

When not aiming specifically at any location, the likelihood of hitting each body part is approximately as shown in the following table:

Location	Chance
arms (either)	19.7%
legs (either)	16.5%
chest	14.7%
abdomen	12.1%
back	10.1%
hands (either)	9.0%
neck	7.4%
eyes (either)	5.3%
head	5.2%

Damage

Main article: Standard damage calculation explained

The system takes the result of the successful attack roll and subtracts 100, then multiplies the weapon's damage factor to obtain the raw damage. Based on the raw damage and the armor type, the system then assigns critical damage with some minor random variation. The defender takes HP damage equal to the raw damage plus the critical damage, and suffers a wound to the specific body location based only on the critical damage and its type (for example, a slashing weapon will deal different criticals than a fireball).

Redux

Main article: Redux

Characters with extensive physical training may reduce the damage taken by a successful attack roll. This effect increases with training in physical skills and decreases when learning magical spells.

Warding Roll

Main article: Warding

Warding Rolls, or CS/TD Checks, are used for a subclass of magical attack spells. Unlike attack rolls, a warding roll does not depend on the attacker or defender's stance.

CS/TD Check

A typical warding roll looks like this:

You gesture at a hill troll.
A hill troll is suddenly surrounded by a circle of crystalline ice shards.
  CS: +186 - TD: +55 + CvA: +11 + d100: +19 == +161
  Warding failed!
The crystalline ice shards quickly orbit the troll, causing 24 points of damage!
   ... 15 points of damage!
   Icy blast to the head and the hill troll is reeling!
   The hill troll is stunned!

In warding roll, the attacker's Casting Strength (CS) is compared against the defender's Target Defense (TD), plus a Cast versus Armor (CvA) value based on the defender's armor. Finally, a random number from 1 to 100 (d100) is added to the result. If the final result is greater than 100, the attack is successful. The higher the result is, the more effective the attack will generally be.

Casting Strength is mainly based on the attacker's Spell Research and mental statistics. Aura is the governing statistic for Elemental spells, and Wisdom for Spiritual spells. Mental spells use a more varied system; for the currently implemented Minor Mental circle, the governing attack statistic is Logic.

Target Defense is mainly based on the defender's level, statistics, and protective magics, and can vary depending on whether the spell is Elemental, Spiritual, or Mental in nature. The defender's race may confer a bonus or penalty to specific types of spells.

Armor is the main (often the only) factor in CvA. Heavier armors are more protective (lower CvA values), making warding spells harder to land. Unlike with attack rolls, armor does not directly reduce damage taken if a warding spell successfully hits, aside from lowering the end result of the roll. However, special armor with padding or resistance to specific types of criticals may reduce damage in some cases.

Disabling Spells

If a warding spell is not intended to deal any direct damage but only inflicts a debilitating status effect, then in general the duration and magnitude of the effect depends on the end result of the warding roll. If the result only exceeds 100 by a small amount, the spell may have very little effect. For example, Sleep induces momentary drowsiness for lower results and only makes the target fully unconscious if the result is high enough.

A few spells such as Pious Trial take full effect as long as the end result is above 100.

Direct Damage Spells

Warding spells that deal direct damage work in a similar way to attack rolls: the end result, minus 100, is multiplied by a damage factor to obtain raw damage, and then separate critical damage is added to a random body location. However, there are many more modifiers specific to each spell, some of which are random, and players may see very different damage outcomes even with the same roll result.

Combat Maneuvers

Main article: Combat Maneuvers

Combat Maneuvers (CMAN) are physical utility skills that consume stamina. Players can attempt combat maneuvers with the appropriate CMAN or SHIELD training.

A typical combat maneuver looks like this:

You lunge forward at a plains orc shaman with your golvern shield and attempt a shield bash!
[Roll result: 192 (open d100: 81) Penalties: 5]
Terrific bash and a plains orc shaman flips end over end and lands on her head!
   ... 15 points of damage!
   Smack to the eye bursts blood vessels.
   The plains orc shaman is stunned!
Roundtime: 5 sec.

The roll result is obtained by adding an open d100 roll, a visible bonuses or penalties score based on transitory factors including wounds, encumbrance, and relative height difference between the attacker and defender, and a hidden skill modifier based mainly on CMAN training. If the result is greater than 100, then the maneuver is successful. The higher the result is, the more effective the maneuver will generally be.

An open roll is a random number which is likely to be between 1 and 100 but has a small chance of exceeding the bounds, with a 5% chance to be a negative number and a 5% chance to be greater than 100.

Standard Maneuver Roll

Main article: Standard maneuver roll

Standard Maneuver Rolls (SMR) are used for a variety of situations. They are generally open d100 rolls with skill modifiers, but the roll result is not visible to the player.

Despite the similarity in name, they do not use the same resolution system as Combat Maneuvers.

A typical standard maneuver roll looks like this:

A gust of wind tugs at your sleeves. Suddenly, a fierce wind rips through the area, scattering everything in its path and making it difficult to remain standing.
The wind knocks you off your balance and you fall over.
Your arms are forced down to your sides!
Roundtime: 5 sec.

Physical Fitness is the primary factor in defending against standard maneuver rolls.

Unarmed Combat

Main article: Unarmed combat system

The Unarmed Combat (UAC) system is used for the melee moves JAB, PUNCH, KICK, and GRAPPLE. It is mainly useful for characters with extensive training in Brawling.

UAF/UDF/MM Check

A typical unarmed combat roll looks like this:

You attempt to jab a minotaur warrior!
You have good positioning against a minotaur warrior.
UAF: 540 vs UDF: 485 = 1.113 * MM: 84 + d100: 76 = 169
   ... and hit for 10 points of damage!
   Light punch to stomach makes the minotaur warrior gasp.
   Strike leaves foe vulnerable to a followup punch attack!
Roundtime: 3 sec.

The attacker's Unarmed Attack Factor (UAF) is compared against the defender's Unarmed Defense Factor (UDF). Unarmed combat computes the ratio (instead of the difference) between attack and defense. The ratio is then multiplied by a Multiplier Modifier (MM) based on the current combat situation. Finally, a random number from 1 to 100 (d100) is added to the result. If the final result is greater than 100, the attack is successful. The higher the result is, the more damaging the attack will generally be.

Unarmed Attack Factor is based primarily on the attacker's Brawling skill. It does not depend on the attacker's stance. Most effects that add to Attack Strength for AS/DS checks also add to UAF.

Unarmed Defense Factor is based primarily on defender's overall defensive ability, which does depend on their stance. Most effects that add to Defensive Strength for AS/DS checks also add to UDF.

The computed ratio between UAF and UDF is capped at 2.000.

Multiplier Modifier is based on the attacker's stance and various other transitory conditions. The average MM in offensive stance is 100.

Damage Calculation

On successful unarmed attacks, raw damage is calculated by taking the end result of the roll, subtracting 100, and multiplying by the Damage Factor of the type of attack. Additional critical damage is assigned based on positioning (decent, good, or excellent) and the defender's armor.

Equipment

While unarmed combat can be effective without any equipment, specialized gloves and boots can be used to enhance combat ability by carrying enchantment bonuses and other effects. These items can be identified with the INSPECT command:

You carefully inspect your leather gauntlets.
After a careful inspection you determine that some leather gauntlets are suitable for use in unarmed combat.

A number of brawling weapons can also be used for UAC. Holding brawling weapons in one or both hands increases the attacking damage factor but decreases MM.