diff --git a/src/app/partners/Lithostitched.ts b/src/app/partners/Lithostitched.ts
new file mode 100644
index 00000000..01b14f6f
--- /dev/null
+++ b/src/app/partners/Lithostitched.ts
@@ -0,0 +1,229 @@
+import type { CollectionRegistry, ResourceType, SchemaRegistry } from '@mcschema/core'
+import { BooleanNode, Case, ChoiceNode, ListNode, Mod, NumberNode, ObjectNode, Opt, Reference as RawReference, StringNode as RawStringNode, Switch } from '@mcschema/core'
+
+
+const ID = 'lithostitched'
+
+export function initLithostitched(schemas: SchemaRegistry, collections: CollectionRegistry) {
+	const Reference = RawReference.bind(undefined, schemas)
+	const StringNode = RawStringNode.bind(undefined, collections)
+
+	const Tag = (id: Exclude<ResourceType, `$tag/${string}`>) =>
+		ChoiceNode(
+			[
+				{
+					type: 'string',
+					node: StringNode({
+						validator: 'resource',
+						params: { pool: id, allowTag: true },
+					}),
+					change: (v: unknown) => {
+						if (
+							Array.isArray(v) &&
+							typeof v[0] === 'string' &&
+							!v[0].startsWith('#')
+						) {
+							return v[0]
+						}
+						return undefined
+					},
+				},
+				{
+					type: 'list',
+					node: ListNode(
+						StringNode({ validator: 'resource', params: { pool: id } })
+					),
+					change: (v: unknown) => {
+						if (typeof v === 'string' && !v.startsWith('#')) {
+							return [v]
+						}
+						return []
+					},
+				},
+			],
+			{ choiceContext: 'tag' }
+		)
+
+	// Worldgen Modifiers
+	const MobCategorySpawnSettings = Mod(
+		ObjectNode({
+			type: StringNode({
+				validator: 'resource',
+				params: { pool: 'entity_type' },
+			}),
+			weight: NumberNode({ integer: true }),
+			minCount: NumberNode({ integer: true }),
+			maxCount: NumberNode({ integer: true }),
+		}),
+		{
+			category: () => 'pool',
+			default: () => [
+				{
+					type: 'minecraft:bat',
+					weight: 1,
+				},
+			],
+		}
+	)
+
+	collections.register(`${ID}:modifier_type`, [
+		'lithostitched:add_biome_spawns',
+		'lithostitched:add_features',
+		'lithostitched:add_structure_set_entries',
+		'lithostitched:add_surface_rule',
+		'lithostitched:add_template_pool_elements',
+		'lithostitched:no_op',
+		'lithostitched:redirect_feature',
+		'lithostitched:remove_biome_spawns',
+		'lithostitched:remove_features',
+		'lithostitched:remove_structures_from_structure_set',
+		'lithostitched:replace_climate',
+		'lithostitched:replace_effects',
+	])
+
+	collections.register(`${ID}:modifier_predicate_type`, [
+		'lithostitched:all_of',
+		'lithostitched:any_of',
+		'lithostitched:mod_loaded',
+		'lithostitched:not',
+		'lithostitched:true',
+	])
+
+	schemas.register(`${ID}:worldgen_modifier`, Mod(ObjectNode({
+		type: StringNode({ validator: 'resource', params: { pool: `${ID}:modifier_type` as any } }),
+		predicate: Opt(Reference(`${ID}:modifier_predicate`)),
+		[Switch]: [{ push: 'type' }],
+		[Case]: {
+			'lithostitched:add_biome_spawns': {
+				biomes: Tag('$worldgen/biome'),
+				spawners: ChoiceNode([
+					{
+						type: 'object',
+						node: MobCategorySpawnSettings,
+						change: (v: any) => v[0],
+					},
+					{
+						type: 'list',
+						node: ListNode(MobCategorySpawnSettings),
+						change: (v: any) => Array(v),
+					},
+				]),
+			},
+			'lithostitched:add_features': {
+				biomes: Tag('$worldgen/biome'),
+				features: Tag('$worldgen/configured_feature'),
+				step: StringNode({ enum: 'decoration_step' }),
+			},
+			'lithostitched:add_structure_set_entries': {
+				structure_set: StringNode({ validator: 'resource', params: { pool: '$worldgen/structure_set' } }),
+				entries: ListNode(
+					ObjectNode({
+						structure: StringNode({ validator: 'resource', params: { pool: '$worldgen/structure' } }),
+						weight: NumberNode({ integer: true, min: 1 }),
+					})
+				),
+			},
+			'lithostitched:add_surface_rule': {
+				levels: ListNode(StringNode({ validator: 'resource', params: { pool: '$dimension' } })),
+				surface_rule: Reference('material_rule'),
+			},
+			'lithostitched:add_template_pool_elements': {
+				template_pool: StringNode({ validator: 'resource', params: { pool: '$worldgen/template_pool' } }),
+				elements: ListNode(
+					Reference('template_weighted_element')
+				),
+			},
+			'lithostitched:redirect_feature': {
+				placed_feature: StringNode({ validator: 'resource', params: { pool: '$worldgen/placed_feature' } }),
+				redirect_to: StringNode({ validator: 'resource', params: { pool: '$worldgen/configured_feature' } }),
+			},
+			'lithostitched:remove_biome_spawns': {
+				biomes: Tag('$worldgen/biome'),
+				mobs: Tag('entity_type'),
+			},
+			'lithostitched:remove_features': {
+				biomes: Tag('$worldgen/biome'),
+				features: Tag('$worldgen/configured_feature'),
+				step: StringNode({ enum: 'decoration_step' }),
+			},
+			'lithostitched:remove_structures_from_structure_set': {
+				structure_set: StringNode({ validator: 'resource', params: { pool: '$worldgen/structure_set' } }),
+				structures: ListNode(
+					StringNode({ validator: 'resource', params: { pool: '$worldgen/structure' } })
+				),
+			},
+			'lithostitched:replace_climate': {
+				biomes: Tag('$worldgen/biome'),
+				climate: ObjectNode({
+					temperature: NumberNode(),
+					downfall: NumberNode(),
+					has_precipitation: BooleanNode(),
+					temperature_modifier: Opt(StringNode({ enum: ['none', 'frozen'] })),
+				}),
+			},
+			'lithostitched:replace_effects': {
+				biomes: Tag('$worldgen/biome'),
+				effects: ObjectNode({
+					sky_color: Opt(NumberNode({ color: true })),
+					fog_color: Opt(NumberNode({ color: true })),
+					water_color: Opt(NumberNode({ color: true })),
+					water_fog_color: Opt(NumberNode({ color: true })),
+					grass_color: Opt(NumberNode({ color: true })),
+					foliage_color: Opt(NumberNode({ color: true })),
+					grass_color_modifier: Opt(StringNode({ enum: ['none', 'dark_forest', 'swamp'] })),
+					ambient_sound: Opt(StringNode()),
+					mood_sound: Opt(ObjectNode({
+						sound: StringNode(),
+						tick_delay: NumberNode({ integer: true }),
+						block_search_extent: NumberNode({ integer: true }),
+						offset: NumberNode(),
+					})),
+					additions_sound: Opt(ObjectNode({
+						sound: StringNode(),
+						tick_chance: NumberNode({ min: 0, max: 1 }),
+					})),
+					music: Opt(ObjectNode({
+						sound: StringNode(),
+						min_delay: NumberNode({ integer: true, min: 0 }),
+						max_delay: NumberNode({ integer: true, min: 0 }),
+						replace_current_music: BooleanNode(),
+					})),
+					particle: Opt(ObjectNode({
+						options: ObjectNode({
+							type: StringNode(),
+						}),
+						probability: NumberNode({ min: 0, max: 1 }),
+					})),
+				}),
+			},
+		},
+	}, { context: `${ID}.worldgen_modifier`, disableSwitchContext: true }), {
+		default: () => ({
+			type: `${ID}:add_features`,
+			biomes: '#minecraft:is_overworld',
+			features: 'example:ore_ruby',
+			step: 'underground_ores',
+		}),
+	}))
+
+	schemas.register(`${ID}:modifier_predicate`, ObjectNode({
+		type: StringNode({ validator: 'resource', params: { pool: `${ID}:modifier_predicate_type` as any } }),
+		[Switch]: [{ push: 'type' }],
+		[Case]: {
+			'lithostitched:all_of': {
+				predicates: ListNode(Reference(`${ID}:modifier_predicate`)),
+			},
+			'lithostitched:any_of': {
+				predicates: ListNode(Reference(`${ID}:modifier_predicate`)),
+			},
+			'lithostitched:mod_loaded': {
+				mod_id: StringNode(),
+			},
+			'lithostitched:not': {
+				predicate: Reference(`${ID}:modifier_predicate`),
+			},
+		},
+	}, {
+		context: `${ID}.modifier_predicate`, disableSwitchContext: true,
+	}))
+}
diff --git a/src/app/partners/index.ts b/src/app/partners/index.ts
index 7300a2c3..f43b3067 100644
--- a/src/app/partners/index.ts
+++ b/src/app/partners/index.ts
@@ -1,10 +1,13 @@
 import type { CollectionRegistry, SchemaRegistry } from '@mcschema/core'
 import { initImmersiveWeathering } from './ImmersiveWeathering.js'
+import { initLithostitched } from './Lithostitched.js'
 import { initObsidian } from './Obsidian.js'
 
 export * from './ImmersiveWeathering.js'
+export * from './Lithostitched.js'
 
 export function initPartners(schemas: SchemaRegistry, collections: CollectionRegistry) {
 	initImmersiveWeathering(schemas, collections)
+	initLithostitched(schemas, collections)
 	initObsidian(schemas, collections)
 }
diff --git a/src/app/partners/locales/en.json b/src/app/partners/locales/en.json
index 7a05495d..154279ce 100644
--- a/src/app/partners/locales/en.json
+++ b/src/app/partners/locales/en.json
@@ -55,8 +55,24 @@
   "immersive_weathering:rule_test.immersive_weathering:block_set_match": "Block set match",
   "immersive_weathering:rule_test.immersive_weathering:fluid_match": "Fluid match",
   "immersive_weathering:rule_test.immersive_weathering:tree_log": "Tree log",
-  "rule_test.blocks": "Blocks",
-  "rule_test.fluid": "Fluid",
+
+  "lithostitched:modifier_type.lithostitched:add_biome_spawns": "Add biome spawns",
+  "lithostitched:modifier_type.lithostitched:add_features": "Add features",
+  "lithostitched:modifier_type.lithostitched:add_structure_set_entries": "Add structure set entries",
+  "lithostitched:modifier_type.lithostitched:add_surface_rule": "Add surface rule",
+  "lithostitched:modifier_type.lithostitched:add_template_pool_elements": "Add template pool elements",
+  "lithostitched:modifier_type.lithostitched:no_op": "Nothing",
+  "lithostitched:modifier_type.lithostitched:redirect_feature": "Redirect feature",
+  "lithostitched:modifier_type.lithostitched:remove_biome_spawns": "Remove biome spawns",
+  "lithostitched:modifier_type.lithostitched:remove_features": "Remove features",
+  "lithostitched:modifier_type.lithostitched:remove_structures_from_structure_set": "Remove structures from set",
+  "lithostitched:modifier_type.lithostitched:replace_climate": "Replace climate",
+  "lithostitched:modifier_type.lithostitched:replace_effects": "Replace effects",
+  "lithostitched:modifier_predicate_type.lithostitched:all_of": "All of",
+  "lithostitched:modifier_predicate_type.lithostitched:any_of": "Any of",
+  "lithostitched:modifier_predicate_type.lithostitched:mod_loaded": "Mod loaded",
+  "lithostitched:modifier_predicate_type.lithostitched:not": "Not",
+  "lithostitched:modifier_predicate_type.lithostitched:true": "True",
 
   "obsidian:item.information": "Item Information",
   "obsidian:item_information.rarity": "Rarity",
@@ -115,5 +131,8 @@
   "obsidian:block.display.model": "Model",
   "obsidian:block.display.item_model": "Item Model",
   "obsidian:block.display.block_model": "Block Model",
-  "obsidian:block.display.lore": "Lore"
+  "obsidian:block.display.lore": "Lore",
+
+  "rule_test.blocks": "Blocks",
+  "rule_test.fluid": "Fluid"
 }
diff --git a/src/app/schema/renderHtml.tsx b/src/app/schema/renderHtml.tsx
index 162f541d..aa986b3c 100644
--- a/src/app/schema/renderHtml.tsx
+++ b/src/app/schema/renderHtml.tsx
@@ -15,7 +15,7 @@ import type { BlockStateRegistry, VersionId } from '../services/index.js'
 import { CachedDecorator, CachedFeature } from '../services/index.js'
 import { ModelWrapper } from './ModelWrapper.js'
 
-const selectRegistries = ['loot_table.type', 'loot_entry.type', 'function.function', 'condition.condition', 'criterion.trigger', 'recipe.type', 'dimension.generator.type', 'dimension.generator.biome_source.type', 'dimension.generator.biome_source.preset', 'carver.type', 'feature.type', 'decorator.type', 'feature.tree.minimum_size.type', 'block_state_provider.type', 'trunk_placer.type', 'foliage_placer.type', 'tree_decorator.type', 'int_provider.type', 'float_provider.type', 'height_provider.type', 'structure_feature.type', 'surface_builder.type', 'processor.processor_type', 'rule_test.predicate_type', 'pos_rule_test.predicate_type', 'template_element.element_type', 'block_placer.type', 'block_predicate.type', 'material_rule.type', 'material_condition.type', 'structure_placement.type', 'density_function.type', 'root_placer.type', 'entity.type_specific.cat.variant', 'entity.type_specific.frog.variant', 'rule_block_entity_modifier.type', 'pool_alias_binding.type']
+const selectRegistries = ['loot_table.type', 'loot_entry.type', 'function.function', 'condition.condition', 'criterion.trigger', 'recipe.type', 'dimension.generator.type', 'dimension.generator.biome_source.type', 'dimension.generator.biome_source.preset', 'carver.type', 'feature.type', 'decorator.type', 'feature.tree.minimum_size.type', 'block_state_provider.type', 'trunk_placer.type', 'foliage_placer.type', 'tree_decorator.type', 'int_provider.type', 'float_provider.type', 'height_provider.type', 'structure_feature.type', 'surface_builder.type', 'processor.processor_type', 'rule_test.predicate_type', 'pos_rule_test.predicate_type', 'template_element.element_type', 'block_placer.type', 'block_predicate.type', 'material_rule.type', 'material_condition.type', 'structure_placement.type', 'density_function.type', 'root_placer.type', 'entity.type_specific.cat.variant', 'entity.type_specific.frog.variant', 'rule_block_entity_modifier.type', 'pool_alias_binding.type', 'lithostitched.worldgen_modifier.type', 'lithostitched.modifier_predicate.type']
 const hiddenFields = ['number_provider.type', 'score_provider.type', 'nbt_provider.type', 'int_provider.type', 'float_provider.type', 'height_provider.type']
 const flattenedFields = ['feature.config', 'decorator.config', 'int_provider.value', 'float_provider.value', 'block_state_provider.simple_state_provider.state', 'block_state_provider.rotated_block_provider.state', 'block_state_provider.weighted_state_provider.entries.entry.data', 'rule_test.block_state', 'structure_feature.config', 'surface_builder.config', 'template_pool.elements.entry.element', 'decorator.block_survives_filter.state', 'material_rule.block.result_state']
 const inlineFields = ['loot_entry.type', 'function.function', 'condition.condition', 'criterion.trigger', 'dimension.generator.type', 'dimension.generator.biome_source.type', 'feature.type', 'decorator.type', 'block_state_provider.type', 'feature.tree.minimum_size.type', 'trunk_placer.type', 'foliage_placer.type', 'tree_decorator.type', 'block_placer.type', 'rule_test.predicate_type', 'processor.processor_type', 'template_element.element_type', 'nbt_operation.op', 'number_provider.value', 'score_provider.name', 'score_provider.target', 'nbt_provider.source', 'nbt_provider.target', 'generator_biome.biome', 'block_predicate.type', 'material_rule.type', 'material_condition.type', 'density_function.type', 'root_placer.type', 'entity.type_specific.type', 'glyph_provider.type', 'sprite_source.type', 'rule_block_entity_modifier.type', 'immersive_weathering.area_condition.type', 'immersive_weathering.block_growth.growth_for_face.entry.direction', 'immersive_weathering.position_test.predicate_type', 'pool_alias_binding.type']
diff --git a/src/config.json b/src/config.json
index 5d4a8118..82e459ce 100644
--- a/src/config.json
+++ b/src/config.json
@@ -538,6 +538,14 @@
       "schema": "immersive_weathering:block_growth",
       "minVersion": "1.18.2"
     },
+    {
+      "id": "lithostitched.worldgen_modifier",
+      "url": "lithostitched/worldgen-modifier",
+      "path": "lithostitched/worldgen_modifier",
+      "tags": ["partners"],
+      "schema": "lithostitched:worldgen_modifier",
+      "minVersion": "1.20.2"
+    },
     {
       "id": "obsidian.item",
       "url": "obsidian/item",
diff --git a/src/locales/en.json b/src/locales/en.json
index 8b2bbd36..466a67aa 100644
--- a/src/locales/en.json
+++ b/src/locales/en.json
@@ -175,6 +175,8 @@
   "partner.obsidian": "Obsidian",
   "generator.obsidian.item": "Obsidian Item",
   "generator.obsidian.block": "Obsidian Block",
+  "partner.lithostitched": "Lithostitched",
+  "generator.lithostitched.worldgen_modifier": "Worldgen Modifier",
   "presets": "Presets",
   "preview": "Visualize",
   "preview.auto_scroll": "Auto scroll",