Spawner modifiers

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OfficialRell edited this page Jul 31, 2026 · 8 revisions

Spawner modifiers are special items that players can apply to a spawner to change how it behaves.

Examples include reducing the health of spawned mobs, applying potion effects, or adjusting the value of a spawner upgrade. Each modifier is configured in the modifiers.yml file.

Modifiers can be applied to a spawner in the upgrade GUI by clicking on the modifier in the bottom inventory. Modifiers can be removed by clicking on the modifier item in the upgrade GUI.

A modifier stays active on the spawner until it runs out of usages (if a usage limit is set), or until the player removes it.

Creating a modifier

Every modifier is defined under the Modifiers section and is identified by a unique key.

The file contains one example modifier – generic. To add a new modifier, copy the entire generic block and paste it below, then change generic to your chosen key and adjust the values.

Modifiers:
  generic:       # the modifier key
    display: ...
    item: ...
    requirements: ...
    effect: ...
 
  new_modifier:   # your new modifier
    display: ...
    ...

Modifier structure

Display name

display: "<red-#ffbf00>Health reduction"

A name shown to players when they apply or remove the modifier.

Item

Defines the modifier item that will be given to players.

item:
  material: PAPER
  name: "<#red-#ffbf00>Health reduction modifier <#bfffff>(-%value%%)"
  lore:
  - ""
  - "<#8fbfbf><!italic>Reduces mob health by %value% percent"
  - "  <#8fbfbf><!italic>upon spawning."
  model: 0
  glint: true

material - item material type.
name - display name, supports placeholders (see Parameters and placeholders).
lore - item description, supports placeholders.
model - custom model data value, set to 0 to disable.
glint - whether the item has enchantment glint

Requirements

Requirements control which spawners a modifier can be applied to.

requirements:
  spawner-level: 0
  spawner-types:
    list: []
    invert: false

spawner-level - minimum spawner level required before this modifier can be applied; a spawner's level equals the total number of upgrade levels across all of its upgrades (e.g. a spawner with no upgrades is level 0; one level-up in each of the 6 upgrade types makes it level 6). You can use * %required_level% placeholder in the item name or lore to display this number.
spawner-types:
- list - list of spawner types this modifier can be applied to (e.g. [ZOMBIE, SKELETON]). Leave empty ([]) to allow all types.
- invert - when false (default), list is a whitelist; when true, list becomes a blacklist.

Effect

The effect section defines what the modifier does. The required fields vary by effect type — see Effect types below.

effect:
  type: EVALUATE_HEALTH
  evaluate-type: SUBTRACT_PERCENT

Effect types

EVALUATE_HEALTH

Modifies the maximum health of every mob that spawns from the spawner.

effect:
  type: EVALUATE_HEALTH
  evaluate-type: <evaluate type>   # see evaluate types

Parameters required when giving the modifier item:

value - amount to apply (must be greater than 0).
usage - how many times this modifier activates before it stops working; use #infinite for unlimited activations.
chance - chance (1–100) that the modifier activates each time a mob spawns; use 100 for it to always activate.

EVALUATE_DAMAGE

Modifies the attack damage of every mob that spawns from the spawner.

effect:
  type: EVALUATE_DAMAGE
  evaluate-type: <evaluate type>   # see evaluate types

Parameters required when giving the modifier item:

value - amount to apply (must be greater than 0).
usage - how many times this modifier activates before it stops working; use #infinite for unlimited activations.
chance - chance (1–100) that the modifier activates each time a mob spawns; use 100 for it to always activate.

EVALUATE_SCALE

Modifies the scale of every mob that spawns from the spawner.

effect:
  type: EVALUATE_SCALE
  evaluate-type: <evaluate type>   # see evaluate types

Parameters required when giving the modifier item:

value - amount to apply (must be greater than 0).
usage - how many times this modifier activates before it stops working; use #infinite for unlimited activations.
chance - chance (1–100) that the modifier activates each time a mob spawns; use 100 for it to always activate.

EVALUATE_UPGRADE

Modifies the value of one of the spawner's upgrades — for example, increasing the spawn range or decreasing the spawn delay. This modifier does not use usage or chance.

effect:
  type: EVALUATE_UPGRADE
  evaluate-type: <evaluate type>   # see evaluate types
  upgrade-type: <upgrade type>     # see upgrade types

Parameters required when giving the modifier item:

value - amount to apply to the upgrade value (must be greater than 0).

GIVE_POTION

Applies a potion effect to every mob that spawns from the spawner.

effect:
  type: GIVE_POTION
  potion-type: <potion type>   # e.g. poison, slowness, strength

Parameters required when giving the modifier item:

duration - how long the potion effect lasts, in ticks (20 ticks = 1 second); use #infinite for an infinite duration; must be greater than 0.
amplifier - strength level of the effect (e.g. 1 = level I, 2 = level II); must be greater than 0.
usage - how many times this modifier activates before stopping. use #infinite for unlimited; must be greater than 0.
chance - activation chance per spawn (1–100).

Evaluate types

The evaluate-type field controls how the value is applied to the base stat.

Type	Description
`ADD`	Adds `value` directly to the base value.
`SUBTRACT`	Subtracts `value` from the base value.
`MULTIPLY`	Multiplies the base value by `value`.
`DEVIDE`	Divides the base value by `value`.
`ADD_PERCENT`	Adds `value`% of the base value to the base value.
`SUBTRACT_PERCENT`	Subtracts `value`% of the base value from the base value.

Example: If a mob's base health is 20 and evaluate-type is SUBTRACT_PERCENT with value set to 50, the mob spawns with 10 health.

Upgrade types

Used only by the EVALUATE_UPGRADE effect to choose which upgrade stat is affected.

Type	Description
`RANGE`	The range within which a player must be for the spawner to activate.
`DELAY`	The delay between spawner spawn cycles.
`AMOUNT`	The number of entities spawned per cycle.
`NEARBY`	The maximum number of nearby entities before spawning is suppressed.
`XP`	The percentage increase in XP dropped.
`DROPS`	The percentage increase in item drops.

Parameters and placeholders

When a modifier item is given to a player via a command, the command includes parameter values (e.g. the health reduction amount or number of usages). These values can be displayed in the item's name and lore using placeholders.

Placeholder	Description	Used by
`%value%`	The main modifier value (e.g. percentage or flat amount).	All evaluate effects
`%usage%`	The number of activations remaining. Displays ∞ when set to infinite.	All effects with usage
`%chance%`	The activation chance percentage.	All effects with chance
`%duration%`	The potion effect duration in seconds. Displays ∞ when infinite.	`GIVE_POTION`
`%amplifier%`	The potion effect level.	`GIVE_POTION`
`%required_level%`	The minimum spawner level required to apply this modifier.	All modifiers

Note! That some placeholders will display regular numbers, but for some you might want to display Roman numerals and it can be done by adding :r after the placeholder (e.g. %amplifier:r%).

Examples

Below is a complete modifiers.yml with two modifiers: one that reduces mob health and one that applies a poison effect.

Modifiers:
  health_reduction:
    display: "<red>Health reduction"
    effect:
      type: EVALUATE_HEALTH
      evaluate-type: SUBTRACT_PERCENT
    requirements:
      spawner-level: 0
      spawner-types:
        list: []
        invert: false
   item:
     material: PAPER
     name: "<red>Health reduction <gray>(-%value%%)"
     lore:
     - ""
     - "<gray>Reduces mob health by %value%%"
     - "<gray>Usages: %usage%"
     - "<gray>Chance: %chance%%"
     model: 0
     glint: true
 
  poison_spawner:
    display: "<green>Poison spawner"
    effect:
      type: GIVE_POTION
      potion-type: poison
    requirements:
      spawner-level: 3
      spawner-types:
        list: [ZOMBIE, SKELETON, CREEPER]
        invert: false
    item:
      material: FERMENTED_SPIDER_EYE
      name: "<green>Poison modifier <gray>(Poison %amplifier:r%)"
      lore:
      - ""
      - "<gray>Applies Poison %amplifier:r% for %duration%s"
      - "<gray>to each spawned mob."
      - "<gray>Usages: %usage%"
      - "<gray>Chance: %chance%%"
      - ""
      - "<yellow>Requires spawner level %required_level%"
      - "<yellow>Only applies to Zombies, Skeletons and Creepers"
      model: 0
      glint: true