Chests: akumalib:roll_table

A chest places every stack it rolled, so extending one from the outside is simply adding a roll on top. Forge's global loot modifiers are the supported way to do that, and they need a codec registered in Java. That codec is the same for every addon, so AkumaLib registers it as akumalib:roll_table and your addon ships JSON only.

Not for Devil Fruit boxes

Boxes are handled automatically, and a modifier on a box gives the wrong odds. See Devil Fruit boxes.

The three files

Copy-ready templates live in examples/loot-injection/ in the repository, each with its instructions in a _comment key. Minecraft ignores unknown keys in these files, so the comments cost nothing at runtime.

File	Goes to
Forge's modifier index	data/forge/loot_modifiers/global_loot_modifiers.json
the modifier	data/<yourmod>/loot_modifiers/<name>.json
the table it rolls	data/<yourmod>/loot_tables/<path>.json

1. The index

data/forge/loot_modifiers/global_loot_modifiers.json

{
  "replace": false,
  "entries": [
    "yourmod:simple_dungeon"
  ]
}

This is the one file Forge merges across every installed mod.

Keep replace at false

"replace": true discards every loot modifier declared by every other mod.

A modifier that is not listed here is never read

No error and no warning: an unlisted modifier file simply does nothing. It is the first thing to check when a modifier seems ignored.

2. The modifier

data/yourmod/loot_modifiers/simple_dungeon.json

{
  "type": "akumalib:roll_table",
  "conditions": [
    {
      "condition": "forge:loot_table_id",
      "loot_table_id": "minecraft:chests/simple_dungeon"
    }
  ],
  "table": "yourmod:inject/simple_dungeon"
}

• conditions aims the modifier. forge:loot_table_id passes only while the named table is the one being rolled; without it, the modifier fires on every loot table in the game.
• table is the table of yours to roll on top.
• mode is optional; see below.

3. The table it rolls

data/yourmod/loot_tables/inject/simple_dungeon.json

{
  "type": "minecraft:empty",
  "pools": [
    {
      "rolls": 1,
      "bonus_rolls": 0.0,
      "conditions": [
        { "condition": "minecraft:random_chance", "chance": 0.2 }
      ],
      "entries": [
        { "type": "minecraft:item", "name": "yourmod:my_item" }
      ]
    }
  ]
}

In a chest, both numbers mean what they look like: chance is how often your pool adds anything at all, and rolls is how many items it adds when it does.

Rolling your table

1. The table's own top-level functions are skipped. The table is rolled the way vanilla nests one table inside another, which does not apply table-wide functions. Pool-level and entry-level conditions and functions do apply, so put anything table-wide on the pool instead.
2. A typo in table is silent. An unknown table id rolls as an empty table: the chest generates its normal loot and yours never appears.

mode

"mode"	Where your roll goes	For
"append" (default)	after the existing loot	chests, and any container that places everything
"compete"	before the existing loot	a container that keeps only its first match

An unknown mode is an error, not a silent fall back to append.

compete changes what the odds mean

In compete, the chance of your table stops meaning "how many of mine" and starts meaning "the share of the one stack the container hands out that is mine". A table written for compete wants a single pool with a single chance: a second pool can only replace the first at the front of the list.

Use compete only for a container that behaves like a box but whose pool you cannot reach. For Devil Fruit boxes, the automatic injection is strictly better.