MythicMobs Skill Tree Explained

What Is the Skill Tree?

The mythicmobs skill tree is the hierarchy of triggers, conditions, mechanics, and targeters that define how a mob behaves. Every action a MythicMobs creature takes flows through this tree: a trigger fires, conditions are checked, mechanics execute, and targeters determine who or what is affected. Understanding this flow is the key to building complex and interesting boss fights.

The Four Components

Triggers

Triggers are events that start a skill. They are prefixed with ~ in mob configs. Common triggers include:

• ~onSpawn: fires when the mob spawns.
• ~onTimer:<ticks>: fires on a repeating timer.
• ~onDamaged: fires when the mob takes damage.
• ~onAttack: fires when the mob attacks a player.
• ~onDeath: fires when the mob dies.
• ~onCombat: fires when the mob enters combat.

Conditions

Conditions gate whether a skill executes. If any condition fails, the entire skill is skipped.

HealingPulse:
  Conditions:
    - health{h=<50%}
    - incombat true
  Skills:
    - heal{a=20} @self
    - effect:particles{p=HEART;a=10} @self

This skill only fires when the mob is below 50% health and in combat. The mythicmobs skill tree evaluates conditions top-to-bottom, stopping at the first failure.

Mechanics

Mechanics are the actual actions: deal damage, apply potion effects, play sounds, send messages, teleport, summon mobs, and more. MythicMobs includes over 80 built-in mechanics.

# Common mechanics
- damage{a=10}                    # Deal 10 damage
- potion{t=WITHER;d=100;l=2}     # Apply Wither II for 5 seconds
- summon{t=SkeletonMinion;a=3}   # Summon 3 minions
- teleport @target                # Teleport to target
- speak{m="You cannot escape."}  # Say a message
- sound{s=entity.ender_dragon.growl} # Play a sound

Targeters

Targeters determine who or what a mechanic affects. They are prefixed with @.

• @self: the mob itself.
• @target: the mob's current target (usually the nearest player in combat).
• @PlayersInRadius{r=10}: all players within 10 blocks.
• @PIR{r=5}: shorthand for PlayersInRadius.
• @origin: the location where the skill started.

Chaining Skills (Meta Skills)

The real power of the mythicmobs skill tree comes from chaining skills together. A parent skill can call child skills, creating branching behavior trees.

# Mob definition
Skills:
  - skill{s=PhaseCheck} ~onTimer:100

# Phase router
PhaseCheck:
  Skills:
    - skill{s=Phase1Skills} @self ~onTimer:0
  Conditions:
    - health{h=>=50%}

PhaseCheck2:
  Skills:
    - skill{s=Phase2Skills} @self ~onTimer:0
  Conditions:
    - health{h=<50%}

# Phase 1: simple attacks
Phase1Skills:
  Skills:
    - damage{a=6} @target
    - effect:particles{p=FLAME;a=10} @target

# Phase 2: enraged mode
Phase2Skills:
  Skills:
    - damage{a=12} @target
    - potion{t=SPEED;d=60;l=2} @self
    - summon{t=SkeletonMinion;a=2} @self
    - message{msg="&4The guardian enters a frenzy!"} @PIR{r=30}

This creates a two-phase boss. Above 50% health, it uses basic attacks. Below 50%, it deals double damage, speeds up, and summons minions.

Skill Delays and Repeats

BarrageAttack:
  Skills:
    - projectile{t=ARROW;v=2;d=40} @target repeat=5 repeatInterval=5

The repeat and repeatInterval options let a single skill fire multiple times, which is useful for rapid-fire attacks or multi-hit combos.

Debugging the Skill Tree

• Use /mm test cast <skillname> to test a skill on yourself.
• Enable debug mode in config.yml with Debug: true to see skill execution in console.
• Check for YAML indentation errors, they are the most common cause of skills not firing.
• Verify targeter syntax, a missing @ prefix silently skips the targeter.

For your first boss build, see our MythicMobs, Creating Your First Custom Boss guide. For installing MythicMobs, start with How to Install MythicMobs.

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