Combat system

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 is mainly based on the attacker's Weapon skill and their stance.

Defensive Strength is mainly based on the defender's training in various defensive skills such as Dodging, Shield Use, and Weapons, as well as their stance. Armor does not add directly to Defensive Strength (aside from possible enchantment bonuses), but is a major factor in determining how much damage is taken if an attack does land.

Evade-Block-Parry

There is a chance for the defender to avoid an attack outright by evading, blocking, or parrying it, avoiding the AS/DS check. 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 first step in combat will be the opponent's opportunity to evade an attack altogether. Evasion success will be based upon a combination of factors, including the character's Dodging skill, armor hindrance, encumbrance, Agility, Intuition, shield size (increased hindrance with larger shields), stance, the level of the opponent, and some spells, such as Mobility, Mass Blur, and Song of Mirrors.

Block

If the Evade attempt fails, the next step is the opportunity to block the attack. In order to block, the character must have a shield in their left hand. The Block attempt is based on a combination of factors, including the character's Shield Use skill, armor hindrance, encumbrance, Dexterity, Strength, shield size (bonus for the larger shield), stance, and the level of the opponent. Shields provide more benefit when blocking missile and bolt spell attacks than they do against melee attacks. It is not possible, however, to block a bolt spell outright without using a specially enhanced shield.

Parry

Finally, if the attack has not been evaded or blocked, the opponent will attempt to Parry. The character must have a weapon in their right hand to parry (bonus for an additional weapon in the left hand). It is not possible to parry missile weapons or bolt spells without using magically enhanced weapons specifically designed for such parrying (see also: Runestaff). The parry attempt is based on several factors, including the character's relevant Weapon skill, armor hindrance, encumbrance, Dexterity, Strength, stance, and the level of the opponent.

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 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.