Combat system
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 or UAF
The third combat resolution type occurs when a combatant uses the unarmed combat (referred to in general as UAC) based on their brawling skills against an opponent. There are several subtleties in the unarmed combat system that make it a bit more complex than just swinging a blade or tossing a bolt spell. Here, UAF, or the unarmed attack factor for the attacker is always compared against UDF or unarmed defense factor of the defender, to resolve success or failure of the attack. This type of resolution looks like this:
This attack again has four components which function similarly to the preceding resolution types, each component possibly comprised of several factors.
- UAF: 29
The UAF or unarmed attack factor has been calculated to be 29 for this attack. Factors that make up this component include skills, attribute bonuses like STR and AGI, the enchantment properties of UAC-specific boots and gloves, and certain spells such as Strength or Dragonclaw. - UDF: 31
UDF, or the unarmed defense factor has been calculated to be 31 for this attack. Factors that make up this component include character or creature level, dodge and parry abilities, shield use, the enchantment properties of various items, and those defensive spells that help the opponent's defenses.
= 0.935
In the case of unarmed combat, an interim value is calculated and shown. This interim value is simply a ratio derived from the UAF divided by the UDF. Of course, you would like this interim value to be higher than 1.0, and it has a highest potential value of 2.0. - * MM: 125
MM, or Multiplier Modifier, is calculated here to be 125 and is a concept unique to the UAC system. It is a numerical value comprised of various advantages and penalties like the combatant's stance and positioning, equipment like shield or weapon held and armor worn, the opponent's stance and status (i.e. stunned or prone), and the lighting conditions in the room or area. - + d100: 92
A random d100 (random number between 1 and 100).
= 208
The final result is 208 indicating a successful attack. This number is calculated by taking the interim ratio calculated earlier, multiplying that ratio and the multiplier modifier, and then adding the d100 result. The Combat System would use this number to calculate hit point damage, wounds suffered, critical ranks if applicable, and any change based on the critical suffered to the combatant's status.