Viola_Siemens

I will use Forge 47.1.0 for Minecraft 1.20.1 as the example (offical mappings channel). In MinecraftServer$createLevels, vanilla use the following code to add spawners for overworld: List<CustomSpawner> list = ImmutableList.of(new PhantomSpawner(), new PatrolSpawner(), new CatSpawner(), new VillageSiege(), new WanderingTraderSpawner(serverleveldata)); I think it useful to post an event here to add spawners for overworld, and other dimensions. For example: List<CustomSpawner> list = ImmutableList.of(new PhantomSpawner(), new PatrolSpawner(), new CatSpawner(), new VillageSiege(), new WanderingTraderSpawner(serverleveldata)); //change begin AddCustomSpawnersEvent event = new AddCustomSpawnersEvent(ImmutableList.<CustomSpawner>builder().addAll(list), LevelStem.OVERWORLD); MinecraftForge.EVENT_BUS.post(event); LevelStem levelstem = registry.get(LevelStem.OVERWORLD); ServerLevel serverlevel = new ServerLevel(this, this.executor, this.storageSource, serverleveldata, Level.OVERWORLD, levelstem, p_129816_, flag, j, event.getCustomSpawnerBuilder().build(), true, (RandomSequences)null); //change end //... for(Map.Entry<ResourceKey<LevelStem>, LevelStem> entry : registry.entrySet()) { ResourceKey<LevelStem> resourcekey = entry.getKey(); if (resourcekey != LevelStem.OVERWORLD) { ResourceKey<Level> resourcekey1 = ResourceKey.create(Registries.DIMENSION, resourcekey.location()); DerivedLevelData derivedleveldata = new DerivedLevelData(this.worldData, serverleveldata); //change begin AddCustomSpawnersEvent event = new AddCustomSpawnersEvent(ImmutableList.<CustomSpawner>builder(), resourcekey); MinecraftForge.EVENT_BUS.post(event); ServerLevel serverlevel1 = new ServerLevel(this, this.executor, this.storageSource, derivedleveldata, resourcekey1, entry.getValue(), p_129816_, flag, j, event.getCustomSpawnerBuilder().build(), false, randomsequences); //change end worldborder.addListener(new BorderChangeListener.DelegateBorderChangeListener(serverlevel1.getWorldBorder())); this.levels.put(resourcekey1, serverlevel1); net.minecraftforge.common.MinecraftForge.EVENT_BUS.post(new net.minecraftforge.event.level.LevelEvent.Load(levels.get(resourcekey))); } } Now the only way I can add custom spawners is to inject constructor of ServerLevel and modify final member customSpawners.