Mass Combat

The mass combat rules are designed to allow you, the DM, to determine the outcome of battles involving hundreds of combatants with a few die rolls. It also zooms down into the action with enough detail to allow player characters the chance to affect the outcome of a battle.

The system works by giving each creature a **battle rating** based on the creature’s challenge rating. Battle rating is an abstract measure of a creature’s combat effectiveness.

To make managing hundreds, or even thousands, of creatures at a time easier, creatures in the mass combat system are organized into units. A unit might include hundreds of individuals.

Each unit involved in a battle also has a **morale rating**. Morale measures the unit’s motivation to engage in battle. Units with high morale are willing to fight to the death, while ones with low morale are likely to fall apart in the face of adversity.

Commanders play a key role in resolving battles. Each unit has a commander, whose Charisma modifiers applies to initiative and morale.

## Battle Rating

The mass combat rules rely on a creature’s battle rating (BR) to summarize its effectiveness in combat. A creature’s BR is based on its challenge rating (CR), as shown in the Battle Rating by Challenge Rating table. BR encompasses a creature’s attacks, hit points, AC, and special abilities by relying on CR as a summary of its power.

BR starts as a bonus, from +1 to +50. A creature of CR 1 or lower is too weak to provide a BR on its own. The table shows that such creatures provide a +1 bonus when they gather in large enough groups. For instance, five CR 1/2 creatures provide a BR of +1. Smaller groups of CR 1/2 creatures provide no BR.

In combat, a unit’s BR can be reduced by being attacked, going as low as 0 or a negative number. See the “Attacks” section later in these rules for details.

BR coefficient is the number you multiple the number of creatures of that CR in a given unit to get that total battle rating that that type of creature contributes to the unit. For example, if you have a unit of 20 goblins (CR 1/4), you would multiply the number of goblins (20) by the BR coefficientfor CR 1/4 (which is 0.10); i.e. 20 × 0.10 = 2. In this case, the goblins would be BR 2 on their own or contribute BR 2 to part of a mixed unit.

## Creating Units

A unit is a single, cohesive group of soldiers that is organized to fight together. A unit can comprise up to 400 Tiny, Small, or Medium creatures. Larger creatures take up more space when counting toward that limit, as shown in the Creature Size in Units table. To count toward a unit’s limit, a creature must have a BR.

Creature Size in Units
 Small
 Medium
 Large
 Huge
 Gargantuan

For example, a unit could include 50 Large creatures and 200 Medium ones. The total space taken up is 400, 200 for the Large creatures and 200 for the Medium ones.

### Commanders

Each unit must have a commander. The commander needs to be one of the creatures included in the unit but does not count toward determining the unit’s size. Note the commander’s Charisma modifier.

### BR Total

Once you have created a unit, total up the BR values of its creatures, including its commander. The total is the unit’s BR.

For creatures that are mounted, such as knights riding a horse, add the BR for the mounts based on their CR, just as you would for any other creatures.

### Unit Space

A unit takes up a space that measures 100 feet on each side regardless of how many creatures are in it. The unit’s size is an abstraction to make tracking units on the battlefield easy in play.

### Ranged Attackers

A unit can make ranged attacks if all its members, other than its commander, can make an attack with a range of at least 100 feet on an at-will basis. If this is the case, note the shortest maximum range of its members’ ranged attacks. This is the unit’s maximum range.

### Unit Design

It’s best to organize similar or identical creatures into a unit. The rules aim to remain simple by reducing a unit’s abilities to the lowest common denominator.

## Morale Rating

Morale is a rating like an ability score modifier. It
ranges from –10 to +10. These rules sometimes
require a unit to make a check using its morale
rating; roll a d20, add the unit’s morale rating,
and compare the total to the relevant DC, just as
for an ability check.
You select a morale rating for each unit
involved in a battle. Assign the rating based on
how the unit has been treated by its allies and
commanders, the stakes of the battle, the unit’s
investment in the outcome, and any other factors
that you think should play a role.
Morale Ratings
Morale Description
–10 Openly rebellious
–8 Mutinous
–4 Disgruntled
–2 Shaky
0 The typical unit
+2 Motivated
+4 Stalwart
+8 Fanatic
+10 Unbreakable
As a rule of thumb, start a unit’s morale at 0 on
the Morale Ratings table. For each factor that
decreases the unit’s morale, shift one row up the
table. For each factor that improves it, shift one
row down. When you’re done with this exercise,
you have a good idea of the unit’s morale rating.
Or you can simply assign a morale rating based
on your judgment.
Finally, you alter the morale rating based on
the unit commander’s Charisma modifier. Add
the commander’s Charisma modifier to the unit’s
morale, to reflect the commander’s ability to
motivate and lead.

#### Factors Affecting Morale

Here are some of the factors that can reduce a unit’s morale rating:

* poor treatment by a commander or allies
* animosity toward an allied unit
* low or no pay
* no stake in the battle’s outcome
* incompetent or ill-prepared commanders
* a daunting, overwhelming foe
* poor equipment

The reverse of any of those factors can improve morale.

## Running Battles

These rules use a structure like the combat rules
in the Player’s Handbook. The biggest change
centers on resolving attacks, which uses BR
rather than attack rolls, AC, and damage.

### Time

The mass combat rules use a timescale different
from the regular combat rules, with 1 round
representing 1 minute of action. This timescale
accounts for the time and complexity needed to
maneuver hundreds or even thousands of
combatants.

### Initiative

You don’t roll initiative for units. Instead, each
unit has a fixed initiative:
Initiative = 10 + unit morale rating +
commander’s Charisma modifier
Units act in order of initiative, from highest to
lowest as normal. In the event of a tie, randomly
determine the order in which the tied units act.
Determine this once, and then use that order for
the rest of the combat.
As in the regular combat rules, a unit can move
and take one action on its turn (see “Action
Options” below). A unit can use some or all of its
movement before taking its action, and can then
use the rest of its movement after acting.

### Speed

A unit’s speed equals 10 times the lowest speed
of its members. It can use movement modes,
such as flight, only if every member of the unit
can use it. Don’t count the speed of mounted
creatures when determining the unit’s speed and
movement types. The riders use their mounts to
move.

Movement. A unit must stop moving if it
moves adjacent to an enemy unit, and a unit
can’t move if it is adjacent to an enemy unit,
unless it uses the Disengage action that turn.
Otherwise, use the rules for movement from
the Player’s Handbook to resolve how far a unit
can move.

Miniatures. It helps to use miniatures to track
battles of great size. For these rules, use a grid or
hexes with each square/hex measuring 100 feet
on a side and with one miniature per unit.
When moving, a unit can move into a
square/hex if the unit has at least half the
movement needed to enter it available.

### Action Options

When a unit takes its action, it chooses one of the
following action options: Attack, Dash, Defend,
Disengage, or Guard. Each option is described
below.

Attack. An attack is an opposed check between
a unit’s BR and its target’s BR. A unit can attack
at any range that all of its members can make
attacks at. Full details on resolving attacks are
given in the “Attacks” section below.

Dash. A unit that dashes increases its speed for
its turn. This increase equals the unit’s speed.

Defend. A unit that defends focuses on
building a shield wall or otherwise making itself
harder to hurt. Until the end of its next turn,
units that attack it suffer disadvantage on their
BR checks.

Disengage. A unit that is adjacent to an enemy
unit normally can’t move. If the unit takes the
Disengage action, it has the chance to move
away. The unit must immediately make a DC 10
morale check. If it fails, it loses its action and
doesn’t move. If it succeeds, it can move up to
half its speed. During this move, it doesn’t need
to stop if it moves adjacent to an enemy unit.
Guard. A unit that guards prepares to attack
any enemy that draws close to it. The next time
an enemy unit enters a space adjacent to this
unit, it immediately makes an attack against the
enemy unit.

### **Attacks**

Attacks in the mass combat rules use opposed
BR checks to determine which side has the upper
hand.

A unit can attack an adjacent enemy unit if any
creature in the unit is within 5 feet of the target.
It can make an attack at range if all its members
can make ranged attacks that can reach the
target.

When a unit attacks a target, the attacking unit
rolls a d20 and adds its BR, as does the target.
You then compare the results to determine the
result of the fight:

**Tie**. Nothing happens if the attacker and the
target tie.

**Target Wins**. If the target’s total is higher, the
attack has no effect.

**Attacker Wins by 10 or Less**. The attacker
scores casualties, but not enough to break the
target unit. The target’s BR is reduced by 2.

**Attacker Wins by 11 or More**. The attacker
scores heavy casualties on the target. The
target’s BR is reduced by 5, and it must
immediately make a DC 10 morale check. If the
check fails, the unit flees the battle and is
eliminated. Remove it from play.

The attacker can gain advantage or suffer
disadvantage on its BR roll, based on the
following factors:

#### **Advantage**

The attacker is on higher ground, such as uphill from the
defender.
The defender is adjacent to at least one enemy unit,
other than the attacker.

#### **Disadvantage**

The defender is partially behind a wall or similar cover.
The defender is adjacent to at least two friendly units.

### **Morale Checks**

In addition to the morale checks caused by
certain actions, a unit must make a morale check
if certain conditions occur during the battle:

**Casualties.** If a unit is reduced to half or less of
its starting BR, it must immediately make a DC
15 morale check. If it fails, it is eliminated from
the battle. Remove it from play.

**Friendly Casualties.** If a friendly unit within
500 feet of the unit is eliminated, the unit must
immediately make a DC 10 morale check. If it
fails, the unit can’t move or take actions on its
next turn.

**Abstraction and Battle Rating**

Remember that the mass combat rules are designed to
make running big, important battles fast and easy. It
uses BR to summarize a creature’s spells, special
abilities, and so on. There are no special rules for
resistance or spell casting because the rules assume that
CR has already accounted for them.

## Characters in Mass Combat

The real fun of running a mass battle is giving
player characters and important NPCs a chance
to affect the outcome. You might be tempted to
absorb such characters into units and ignore
their special abilities. You can do so by using the
rules for determining CR in the Dungeon Master’s
Guide to assign CRs to the characters. However,
mass battles are more fun for players when they
have a chance to engage in heroics that alter the
course of the fight.
You can give the characters an opportunity to
shine by pausing the large-scale battle and
letting them engage in a regular combat (see
“Character-Scale Combat” below) or by letting
them use their abilities from within a unit (see
“Characters in Units” below).
Character Abilities
Whatever way the characters are involved in a
mass combat, resolve their features, spells, and
other abilities using the standard rules, rather
than the mass combat rules. For example, a wall
of ice can block a 100-foot long line. If a unit
moves next to it, use the individual members’
stats to make their saving throws and apply
damage. If members of a unit are killed,
recalculate the unit’s BR after removing the
casualties.
Adjudicating these effects requires your
judgment as DM. Consider the nature of the
situation, how a unit interacts with a spell or
other effect, and apply the effects as you see fit.
Going back to wall of ice, you might judge that
30 creatures from a unit attempt to smash it
down. Those creatures suffer the wall’s effects,
but they also have a chance to damage it. Use the
rules for handling mobs on page 250 of the
Dungeon Master’s Guide to speed things up.
Character-Scale Combat
You can think of the mass combat rules as
looking at a battle from high altitude. You lose
detail but can see and manage the big picture.
When PCs take part in a battle, your view can
zoom down to experience the action in more
detail.
When characters battle units, you can use the
standard combat rules, with the guidelines for
resolving mob attacks (see “Handling Mobs” in
the Dungeon Master’s Guide, page 250).
You may decide that all or part of a unit stops
to fight the PCs. Pause the mass battle, and
resolve the characters’ fight like a normal
combat, until you are satisfied that you have
reached a conclusion, with either side defeated
or driven off. You can then resume the mass
combat.
Characters in Units
If the characters join a unit, don’t include them in
the unit’s size or BR calculation. Instead, when
the unit attacks, allow the characters to make
their own separate attacks, cast spells, and to use
magic items against the enemy unit using the
guidelines given above. Allow them to pick out
which members of the unit they want to target,
in case the unit is composed of several types of
creatures. Characters attacking in this manner
can target only creatures included in the target
unit’s BR.
©2017 Wizards of the Coast LLC 5
On the unit’s turn, each character has one turn
to make attacks, cast spells, use a magic item, or
the like. Resolve the characters’ attacks and
spells and determine how many targets they
eliminate. Determine how the loss of those
creatures reduces the unit’s BR, then resolve the
unit fight as normal.
If a spell or effect leaves a creature unable to
move or take actions, count that creature as
eliminated for the rest of the battle.
If the characters’ unit comes under attack,
resolve the fight as normal. The results don’t
apply to the characters. If their unit is
eliminated, they remain on the battlefield and
can continue to act.
Critical Events
In addition to allowing characters to take part in
fights between units, think of critical events that
might take place during the battle and give
characters a chance to take part in those events.
Critical events can include the following:
• Prevent enemy scouts from seizing a bridge or
other position.
• Assassinate an enemy commander.
• Hold attackers away from a gate while friendly
soldiers repair it.
• Sneak into an enemy stronghold to sabotage
its defenses.
• Destroy an approaching siege engine.
• Steal the enemy’s battle plans.
These critical events play out just like short
adventures. You should map the area, determine
the opposition, and prepare any NPCs as needed.
When creating critical events, think about the
consequences for success and failure. What
happens if the PCs manage to destroy a bridge
the enemy needs to cross a river? If the PCs don’t
raise the castle gates by dawn, what happens
next?
The situation at the start of a clash could be
dictated by the PCs’ success or failure
beforehand. An enemy unit might start a battle
in a strong position, lurking in a village with
cover, because the PCs failed to outmaneuver
them. Or the PCs might destroy an evil wizard’s
castle gate, rendering his fortification useless in
the coming battle.
NPCs, PCs, and Battle Rating
You can always calculate a character’s BR and simply
include it in a unit, though the level of abstraction in the
rules removes individual actions from a player’s control.
This approach is best for NPCs who are commanders or
who are background players in the battle.
Treat critical NPCs, such as important villains and
rivals, in the same way you would manage PCs. Let the
players seek them out, for the clash between them is
undoubtedly a critical event in determining how the
battle unfolds.

## Mass Combat Unit Entries

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4th Division (Northern and Eastern Forts)

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The Wolfskulls

Distinguishable by their wolf-skin robes.

Threshold Town Guard

6 levle 1 fighters

1 level 3 sergeant

## Goblin Clans

Wolfskull Clan

battleaxe, axe, spear, wolf cavalry

8 giant ferrets

### **Red-Blade Clan**

sword and sling, giant shrews,

Nimble Escape. Goblin units have advantage on morale checks to disengage.

Melee Vulnerability. Units attacking slingers with a melee attack have advantage.

### **Viper Clan**

war hammers and thrown daggersrock pythos

#### **Yellow-Fang Clan**

plak, showrt sword, bows, giant bats, wild rock baboons

Bloodhead Clan

Vlack's Retinue

5 giant vampire bats

vlack hobgoblin king 2 handed sword, 1 ice wolf, 4 bloodhead hobgoblins, 4 dire wolves

Black Web Orc Clan

orcs, nyx, shadows

Iron Ring

1 reaver 7 hounds of the iron ring + 8 riding horses

Caravan

5 guard leaders

40 normal guards

20 wagon drives