Custom encounter pools

Encounters are datapack JSON. The server config decides which ones a charged pillar can open. You can ship new encounters in a datapack (or KubeJS data/) and point the pool at them without touching the mod jar.

Where files live

data/<namespace>/encounters/<id>.json

Built-in ones are under leylines — for example data/leylines/encounters/leyline_breach.json, which registers as leylines:leyline_breach. Your pack can use any namespace: mypack:crystal_siege from data/mypack/encounters/crystal_siege.json.

/reload (or a world restart) reloads the encounter list.

Encounter JSON shape

{
  "color": "#9B6CFF",
  "waves": [
    {
      "setup_time": 80,
      "max_wave_time": 800,
      "entities": [
        { "entity": "minecraft:enderman", "count": 4 }
      ],
      "rewards": [
        { "item": "minecraft:amethyst_shard", "count": 4 }
      ]
    },
    {
      "setup_time": 120,
      "max_wave_time": 1000,
      "entities": [
        { "entity": "minecraft:evoker", "count": 1 },
        { "entity": "minecraft:vex", "count": 2 }
      ],
      "rewards": [
        { "experience": 250 }
      ]
    }
  ],
  "rewards": [
    { "item": "minecraft:echo_shard", "count": 2 },
    { "experience": 400 }
  ]
}

Fields:

• color — hex tint for the rift (#RRGGBB). Optional; defaults to #9B6CFF.
• waves — required, at least one. Played in order.
  • setup_time — ticks before the wave’s mobs spawn (default 80).
  • max_wave_time — ticks to clear the wave before the rift fails (default 800).
  • entities — list of { "entity": "modid:id", "count": N }. count defaults to 1. Any registered entity id works, including other mods.
  • rewards — optional loot when that wave clears.
• rewards (top level) — optional loot when the whole encounter clears. Ley Crystal chance is separate (config leyCrystalClearChance, default 25%) and is not listed here.

Each reward entry can have:

• "item": "modid:id" plus optional "count" (default 1)
• "experience": N (XP orb)
• both in one object if you want

Copy a built-in file from the jar under data/leylines/encounters/ and edit until it feels right.

Wiring the pool (server config)

In leylines-server.toml (or the Leylines server config screen):

Default pool:

encounterMode = "pool"
encounterPool = [
  "leylines:leyline_breach",
  "leylines:void_rift",
  "leylines:amethyst_surge",
  "leylines:spectral_tide",
  "leylines:chaotic_echo",
  "leylines:ley_storm"
]

To add yours without removing the defaults, append the id:

encounterPool = [
  "leylines:leyline_breach",
  "leylines:void_rift",
  "leylines:amethyst_surge",
  "leylines:spectral_tide",
  "leylines:chaotic_echo",
  "leylines:ley_storm",
  "mypack:crystal_siege"
]

To run only your encounter:

encounterMode = "fixed"
fixedEncounterId = "mypack:crystal_siege"

Or set encounterMode = "pool" with a one-entry list. Unknown or invalid ids are skipped / logged — if the pool ends up empty, the pillar fails to open a rift.

Checklist

1. Drop data/<namespace>/encounters/<id>.json in a datapack enabled for the world.
2. /reload and confirm the log line about loaded leyline encounters went up.
3. Put namespace:id in encounterPool (or set fixedEncounterId).
4. Charge a pillar in-game and clear a wave to verify spawns and rewards.