The material below is open game content.
Resolving Unit Combat
The OMCS follows many of the rules creatures do when they fight using the core d20 system. Unless otherwise stated below, all combat rules detailed in Core Rulebook I apply equally to units, the Unit Roster making this transition relatively easy. Unit combat occurs whenever two units meet in battle and engage in combat. A full summary of unit combat, together with the changes required to rules in Core Rulebook I is presented here.
Unit combat is broken up into 6 second rounds as usual.
Before the first round of unit combat begins, each unit involved makes an Initiative check. An Initiative check is a Dexterity check (1d20 + unit’s Dexterity modifier). If the unit’s leader has the Leadership feat, a +2 competence bonus is applied to their Initiative check.
Units may attack in every round they are in contact with the enemy.
To score a hit that deals damage, a unit must roll the target’s Armour Class or better.
Melee Attack Roll: 1d20 + base attack bonus + Strength modifier + size modifier.
Ranged Attack Roll: 1d20 + base attack bonus + Dexterity modifier + size modifier.
Note that size modifiers refer to creature size as normal, not to the overall Unit Size. Ranged penalties are never used in the OMCS, due to the ease of hitting large units of fighting men at any ranged.
The majority of attacks in the d20 system deal damage in hit points. However, units receive damage in terms of Unit Hit Points, which are effectively the number of Hit Dice of the entire unit.
A unit’s Armour Class is the result needed for an enemy unit to successfully make an attack roll.
Armour Class: 10 + armour bonus + shield bonus + Dexterity modifier + size modifier.
Unit Hit Points
Unit Hit Points represent how much damage a unit can take before they are considered to be wiped out.
When attacking, a unit has two basic options.
Charge: A unit not engaged in melee combat may charge any enemy with this option.
Attack: A unit may make either melee or ranged attacks. Units that can strike more than once each round may do so with this attack option.
Withdraw: If involved in melee combat, a unit may attempt to withdraw.
Individual Unit Members
Any unit member not actively engaged in unit combat may act as normal, following all the combat rules in Core Rulebook I. This includes making attacks of their own, casting spells or any other action permissible.
A unit’s relative position once in unit combat is not truly important. Small scale movement in the description of the combat will not affect the battle.
Attacks of Opportunity
Attacks of opportunity are only used in unit combat when one unit attempts to withdraw from melee combat with another. The act of widrawing from combat generates an attack of opportunity.
The Unit Hit Points are a representation of how much damage a unit can take before they are completely slaughtered or routed. A unit reduced to 0 Unit Hit points are considered vanquished, though they may not all be necessarily slain. Rules for determining how many survive unit combat are covered on p103.
When one unit heavily outmatches another, either in terms of number or ability, they will soon find they are able to cause an incredible amount of damage upon their enemies whilst suffering very little in return. The table below is used to grant attack, damage and morale modifiers to units who heavily outmatch their enemies, or are outmatched in return.
|Unit Size is…||Attack Roll Modifier||Damage Roll Modifier||Morale Modifier|
|Ten times or more enemy’s||+5||x10||+5|
|Five times enemy’s||+3||x5||+3|
|Three times enemy’s||+2||x3||+2|
|50% of enemy’s||-1||x1||-1|
|33% of enemy’s||-2||x1||-2|
|20% of enemy’s||-3||x1||-3|
|10% or less of enemy’s||-5||x½||-5|
If the majority of the unit have a special ability (the Barbarian Rage, for example), then this too applies to unit combat. Bonuses to attack, damage and related rolls are easy to apply to the unit combat system portrayed here. Feats are the only special abilities never used, no matter how many of the unit possess the same one.
The rules for flat-footed combatants are not used in unit combat.
In addition, the followng rules from Core Rulebook I are never used in unit combat.
Magic Actions, Miscellaneous Actions, Injury and Death, Flanking, Aid Another, Bull Rush, Disarm, Grapple, Mounted Combat, Overrun, Trip.
Unit Charge Option
Any unit not currently engaged in melee combat may charge an enemy unit. In doing so, the unit gains the normal +2 charge bonus to its attack roll. However, the unit will also suffer a -2 penalty to its Armour Class for one round. The charge option is the only way in which a unit may initiate melee combat with another.
Unit Attack Option
Unit combat is treated in the same way as combats be3tween creatures in that Initiative chekcs are made, followed by attack and damage rolls. There are, however, some important differences to be aware of.
Unit Ranged Attacks
Many units equip a large portion of their units with bows, crossbows, and other missile weapons. The effect of an entire unit firing or hurling missile weapons can be devastating for whilst soldiers are not always renowned for being accurate marksmen, a huge wave of arrows directed onto a packed enemy unit can cause utter carnage. The use of ballistae on the battlefield takes this kind of warfare to a new level – huge, spear-sized bolts are launched straight into the packed mass of an enemy unit, creating absolute terror as several unit members may be impaled by each bolt.
Firing Ranged Weapons
Ranged attackers make a normal attack roll against their target’s Armour Class, as described in Core Rulebook I.
If a hit is scored, a damage roll is made for normally, with the result being deducted from the target’s Unit Hit Points. This damage roll, however, is modified as shown below, depending on the unit size of the attackers – larger units are able to fire great numbers of missiles, causing an immense amount of damage against their enemies.
|Unit Size of Attackers||Damage Modifier|
|200 or more||x4|
A minimum of 1 point of damage will always be caused, even if the dice roll is modified to 0 or less.
Units with a Unit Size of 5 or less do not use this system – use the normal combat rules described in Core Rulebook I instead.
Huge explosive spells such as fireball can have a devastating effect on the tightly packed mass of a unit, and even a lightning bolt is likely to slay several warriors as it rips through their ranks. Magic is a powerful force on the battlefield and spellcasters are much sought after by generals who delight in both their attack spells, as well as arcane and divine defences.
Spells listed as having a range of touch or close may only be used against an enemy unit with whom the spellcaster is currently engaged in melee combat with. Those of medium range may be used against any unit on the battlefield with the exception of enemy archers. Spells of long range may be used against any unit, including enemy archers.
The Games Master is the final arbitrator as to the ultimate effectiveness of any spell, though the rules provided here will allow him to handle the vast majority of spells available quickly and easily.
Magicks in the OMCS
Any offenseive spell will cause normal damage to a Unit’s Hit Points, even if it normally affects only one subject, due to the close density of fighting men. Any spell that has an area of effect of at least 20 ft. in length, width or radius will cause double its normal damage against a Unit’s Hit Points. Saving trhows and Spell Resistance apply as normal.
Spells that cause affects other than damage (such as bless or bane) will only provide their bonus or penalty to a unit if the majority of its members can be affected. If only a minority are affected by the spell, it provides no benefit or penalty in unit combat. Games Masters should adjudicate how many unit members fall under the effect of such spells, using their creature size as a guide to how much space the unit as a whole covers.
Clerics may attempt to turn and rebuke undead units, despite the far greater numbers than might normally be faced. The rules for turning detailed in Core Rulebook I are used to determine how many Hit Dice of undead are affected as normal, and this total is deducted directly from the undead’s Unit Hit Points.
Unit Withdraw Option
A unit may choose to withdraw if the fight goes against them, either to regroup before launching another attack or to attempt to break off from combat altogether.
A unit attempting to withdraw instead of attacking in a round immediately provokes an attack of opportunity from any enemy in melee combat with them.