modifiers Collection Types

Collection Types Reference

Collections determine which subjects a modifier affects. The modifier system gathers subjects through collections and then applies effects to matching subjects.

How Collections Work

1. Modifier activates (owner meets requirements)
2. Collection gathers potential subjects
3. Subject requirements filter subjects
4. Effect applies to remaining subjects

Available Collection Types

Player Collections

COLLECTION_OWNER

The owner of the modifier itself. Use for effects that apply to the modifier's owner directly.

<Modifier id="EXAMPLE" collection="COLLECTION_OWNER" effect="EFFECT_PLAYER_GRANT_YIELD">
    <Argument name="YieldType">YIELD_GOLD</Argument>
    <Argument name="Amount">100</Argument>
</Modifier>

COLLECTION_PLAYER_CITIES

All cities belonging to the player.

<Modifier id="EXAMPLE" collection="COLLECTION_PLAYER_CITIES" effect="EFFECT_CITY_ADJUST_YIELD">
    <Argument name="YieldType">YIELD_FOOD</Argument>
    <Argument name="Amount">2</Argument>
</Modifier>

COLLECTION_OWNER_CITY

The city that owns the modifier (for building/improvement modifiers).

<Modifier id="EXAMPLE" collection="COLLECTION_OWNER_CITY" effect="EFFECT_CITY_GRANT_UNIT">
    <Argument name="UnitType">UNIT_WARRIOR</Argument>
</Modifier>

Unit Collections

COLLECTION_PLAYER_UNITS

All units belonging to the player.

<Modifier id="EXAMPLE" collection="COLLECTION_PLAYER_UNITS" effect="EFFECT_UNIT_ADJUST_ABILITY">
    <SubjectRequirements>
        <Requirement type="REQUIREMENT_UNIT_TAG_MATCHES">
            <Argument name="Tag">UNIT_CLASS_INFANTRY</Argument>
        </Requirement>
    </SubjectRequirements>
    <Argument name="AbilityType">ABILITY_FIRST_STRIKE</Argument>
</Modifier>

COLLECTION_PLAYER_COMBAT

Player's combat units during combat resolution.

<Modifier id="EXAMPLE" collection="COLLECTION_PLAYER_COMBAT" effect="EFFECT_ADJUST_UNIT_STRENGTH_MODIFIER">
    <Argument name="Amount">5</Argument>
</Modifier>

Plot Collections

COLLECTION_PLAYER_PLOT_YIELDS

Plots that provide yields to the player. Used for plot-based yield bonuses.

<Modifier id="EXAMPLE" collection="COLLECTION_PLAYER_PLOT_YIELDS" effect="EFFECT_PLOT_ADJUST_YIELD">
    <SubjectRequirements>
        <Requirement type="REQUIREMENT_PLOT_RESOURCE_VISIBLE"/>
    </SubjectRequirements>
    <Argument name="YieldType">YIELD_GOLD</Argument>
    <Argument name="Amount">1</Argument>
</Modifier>

Collection + Effect Combinations

Not all collections work with all effects. Common combinations:

Collection	Common Effects
COLLECTION_OWNER	EFFECT_PLAYER_GRANT_YIELD, EFFECT_PLAYER_ADJUST_*, Scoring effects
COLLECTION_PLAYER_CITIES	EFFECT_CITY_ADJUST_YIELD, EFFECT_CITY_GRANT_UNIT, Production effects
COLLECTION_OWNER_CITY	EFFECT_CITY_* effects for building modifiers
COLLECTION_PLAYER_UNITS	EFFECT_UNIT_*, EFFECT_ARMY_* effects
COLLECTION_PLAYER_COMBAT	EFFECT_ADJUST_UNIT_STRENGTH_MODIFIER
COLLECTION_PLAYER_PLOT_YIELDS	EFFECT_PLOT_ADJUST_YIELD

Using Collections with Requirements

Collections gather all potential subjects, then SubjectRequirements filter them:

<Modifier id="COASTAL_CITY_BONUS" collection="COLLECTION_PLAYER_CITIES" effect="EFFECT_CITY_ADJUST_YIELD">
    <SubjectRequirements>
        <Requirement type="REQUIREMENT_PLOT_ADJACENT_TO_COAST"/>
        <Requirement type="REQUIREMENT_CITY_IS_CITY"/>
    </SubjectRequirements>
    <Argument name="YieldType">YIELD_GOLD</Argument>
    <Argument name="Amount">3</Argument>
</Modifier>

This applies +3 gold only to coastal cities (filtering out inland cities and towns).

Examples from Game Files

Trade Route Culture Bonus (Aksum)

<Modifier id="PORT_OF_NATIONS_MOD_TRADE_ROUTE_CULTURE" collection="COLLECTION_OWNER" effect="EFFECT_PLAYER_ADJUST_YIELD_PER_NUM_TRADE_ROUTES">
    <Argument name="YieldType">YIELD_CULTURE</Argument>
    <Argument name="Amount">2</Argument>
</Modifier>

Commander XP Bonus (Greece)

<Modifier id="STRATEGOI_MOD_COMMANDER_XP" collection="COLLECTION_PLAYER_UNITS" effect="EFFECT_ARMY_ADJUST_EXPERIENCE_RATE">
    <SubjectRequirements>
        <Requirement type="REQUIREMENT_UNIT_TAG_MATCHES">
            <Argument name="Tag">UNIT_CLASS_COMMAND</Argument>
        </Requirement>
    </SubjectRequirements>
    <Argument name="Percent">25</Argument>
</Modifier>

Navigable River Food Bonus (Egypt)

<Modifier id="AKHET_MOD_NAVIGABLE_RIVER_FOOD" collection="COLLECTION_PLAYER_PLOT_YIELDS" effect="EFFECT_PLOT_ADJUST_YIELD">
    <SubjectRequirements>
        <Requirement type="REQUIREMENT_PLOT_IS_RIVER">
            <Argument name="Navigable">true</Argument>
        </Requirement>
        <Requirement type="REQUIREMENT_PLOT_DISTRICT_CLASS">
            <Argument name="DistrictClass">RURAL, URBAN, CITYCENTER</Argument>
        </Requirement>
    </SubjectRequirements>
    <Argument name="YieldType">YIELD_FOOD</Argument>
    <Argument name="Amount">2</Argument>
</Modifier>

Database Definition

In traditional database format, collections are defined in DynamicModifiers:

<DynamicModifiers>
    <Row
        ModifierType="MY_MODIFIER_TYPE"
        CollectionType="COLLECTION_PLAYER_CITIES"
        EffectType="EFFECT_CITY_ADJUST_YIELD"
    />
</DynamicModifiers>

See Also

• Effect Types
• Requirement Types
• Modifier System Overview