diff --git a/app/controllers/api/v1/grid_artifacts_controller.rb b/app/controllers/api/v1/grid_artifacts_controller.rb
index b960589..122ff85 100644
--- a/app/controllers/api/v1/grid_artifacts_controller.rb
+++ b/app/controllers/api/v1/grid_artifacts_controller.rb
@@ -3,11 +3,11 @@
 module Api
   module V1
     class GridArtifactsController < Api::V1::ApiController
-      before_action :find_grid_artifact, only: %i[update destroy]
-      before_action :find_party, only: %i[create update destroy]
+      before_action :find_grid_artifact, only: %i[update destroy sync]
+      before_action :find_party, only: %i[create update destroy sync]
       before_action :find_grid_character, only: %i[create]
       before_action :find_artifact, only: %i[create]
-      before_action :authorize_party_edit!, only: %i[create update destroy]
+      before_action :authorize_party_edit!, only: %i[create update destroy sync]
 
       # POST /grid_artifacts
       def create
@@ -50,6 +50,20 @@ module Api
         end
       end
 
+      # POST /grid_artifacts/:id/sync
+      def sync
+        unless @grid_artifact.collection_artifact.present?
+          return render_unprocessable_entity_response(
+            Api::V1::GranblueError.new('No collection artifact linked')
+          )
+        end
+
+        @grid_artifact.sync_from_collection!
+        render json: GridArtifactBlueprint.render(@grid_artifact.reload,
+                                                  root: :grid_artifact,
+                                                  view: :nested)
+      end
+
       private
 
       def find_grid_artifact
@@ -107,7 +121,8 @@ module Api
 
       def grid_artifact_params
         params.require(:grid_artifact).permit(
-          :grid_character_id, :artifact_id, :element, :proficiency, :level, :reroll_slot,
+          :grid_character_id, :artifact_id, :collection_artifact_id,
+          :element, :proficiency, :level, :reroll_slot,
           skill1: %i[modifier strength level],
           skill2: %i[modifier strength level],
           skill3: %i[modifier strength level],
diff --git a/app/controllers/api/v1/grid_characters_controller.rb b/app/controllers/api/v1/grid_characters_controller.rb
index 966b988..1aecc63 100644
--- a/app/controllers/api/v1/grid_characters_controller.rb
+++ b/app/controllers/api/v1/grid_characters_controller.rb
@@ -15,10 +15,10 @@ module Api
     class GridCharactersController < Api::V1::ApiController
       include IdResolvable
 
-      before_action :find_grid_character, only: %i[update update_uncap_level update_position destroy resolve]
-      before_action :find_party, only: %i[create resolve update update_uncap_level update_position swap destroy]
+      before_action :find_grid_character, only: %i[update update_uncap_level update_position destroy resolve sync]
+      before_action :find_party, only: %i[create resolve update update_uncap_level update_position swap destroy sync]
       before_action :find_incoming_character, only: :create
-      before_action :authorize_party_edit!, only: %i[create resolve update update_uncap_level update_position swap destroy]
+      before_action :authorize_party_edit!, only: %i[create resolve update update_uncap_level update_position swap destroy sync]
 
       ##
       # Creates a new grid character.
@@ -226,6 +226,26 @@ module Api
         end
       end
 
+      ##
+      # Syncs a grid character from its linked collection character.
+      #
+      # Copies all customizations from the collection character to this grid character.
+      # Returns 422 if no collection character is linked.
+      #
+      # @return [void]
+      def sync
+        unless @grid_character.collection_character.present?
+          return render_unprocessable_entity_response(
+            Api::V1::GranblueError.new('No collection character linked')
+          )
+        end
+
+        @grid_character.sync_from_collection!
+        render json: GridCharacterBlueprint.render(@grid_character.reload,
+                                                   root: :grid_character,
+                                                   view: :nested)
+      end
+
       private
 
       ##
@@ -526,6 +546,7 @@ module Api
           :id,
           :party_id,
           :character_id,
+          :collection_character_id,
           :position,
           :uncap_level,
           :transcendence_step,
diff --git a/app/controllers/api/v1/grid_summons_controller.rb b/app/controllers/api/v1/grid_summons_controller.rb
index f30e6f7..9f2cda5 100644
--- a/app/controllers/api/v1/grid_summons_controller.rb
+++ b/app/controllers/api/v1/grid_summons_controller.rb
@@ -14,10 +14,10 @@ module Api
 
       attr_reader :party, :incoming_summon
 
-      before_action :find_grid_summon, only: %i[update update_uncap_level update_quick_summon update_position resolve destroy]
-      before_action :find_party, only: %i[create update update_uncap_level update_quick_summon update_position swap resolve destroy]
+      before_action :find_grid_summon, only: %i[update update_uncap_level update_quick_summon update_position resolve destroy sync]
+      before_action :find_party, only: %i[create update update_uncap_level update_quick_summon update_position swap resolve destroy sync]
       before_action :find_incoming_summon, only: :create
-      before_action :authorize_party_edit!, only: %i[create update update_uncap_level update_quick_summon update_position swap destroy]
+      before_action :authorize_party_edit!, only: %i[create update update_uncap_level update_quick_summon update_position swap destroy sync]
 
       ##
       # Creates a new grid summon.
@@ -228,6 +228,23 @@ module Api
         end
       end
 
+      ##
+      # Syncs a grid summon from its linked collection summon.
+      #
+      # @return [void]
+      def sync
+        unless @grid_summon.collection_summon.present?
+          return render_unprocessable_entity_response(
+            Api::V1::GranblueError.new('No collection summon linked')
+          )
+        end
+
+        @grid_summon.sync_from_collection!
+        render json: GridSummonBlueprint.render(@grid_summon.reload,
+                                                root: :grid_summon,
+                                                view: :nested)
+      end
+
       ##
       # Saves the provided grid summon.
       #
@@ -454,8 +471,9 @@ module Api
       #
       # @return [ActionController::Parameters] The permitted parameters.
       def summon_params
-        params.require(:summon).permit(:id, :party_id, :summon_id, :position, :main, :friend,
-                                       :quick_summon, :uncap_level, :transcendence_step)
+        params.require(:summon).permit(:id, :party_id, :summon_id, :collection_summon_id,
+                                       :position, :main, :friend, :quick_summon,
+                                       :uncap_level, :transcendence_step)
       end
 
       ##
diff --git a/app/controllers/api/v1/grid_weapons_controller.rb b/app/controllers/api/v1/grid_weapons_controller.rb
index f6499ed..e9247ac 100644
--- a/app/controllers/api/v1/grid_weapons_controller.rb
+++ b/app/controllers/api/v1/grid_weapons_controller.rb
@@ -12,10 +12,10 @@ module Api
     class GridWeaponsController < Api::V1::ApiController
       include IdResolvable
 
-      before_action :find_grid_weapon, only: %i[update update_uncap_level update_position resolve destroy]
-      before_action :find_party, only: %i[create update update_uncap_level update_position swap resolve destroy]
+      before_action :find_grid_weapon, only: %i[update update_uncap_level update_position resolve destroy sync]
+      before_action :find_party, only: %i[create update update_uncap_level update_position swap resolve destroy sync]
       before_action :find_incoming_weapon, only: %i[create resolve]
-      before_action :authorize_party_edit!, only: %i[create update update_uncap_level update_position swap resolve destroy]
+      before_action :authorize_party_edit!, only: %i[create update update_uncap_level update_position swap resolve destroy sync]
 
       ##
       # Creates a new GridWeapon.
@@ -222,6 +222,23 @@ module Api
         end
       end
 
+      ##
+      # Syncs a grid weapon from its linked collection weapon.
+      #
+      # @return [void]
+      def sync
+        unless @grid_weapon.collection_weapon.present?
+          return render_unprocessable_entity_response(
+            Api::V1::GranblueError.new('No collection weapon linked')
+          )
+        end
+
+        @grid_weapon.sync_from_collection!
+        render json: GridWeaponBlueprint.render(@grid_weapon.reload,
+                                                root: :grid_weapon,
+                                                view: :full)
+      end
+
       private
 
       ##
@@ -476,7 +493,7 @@ module Api
       # @return [ActionController::Parameters] the permitted parameters.
       def weapon_params
         params.require(:weapon).permit(
-          :id, :party_id, :weapon_id,
+          :id, :party_id, :weapon_id, :collection_weapon_id,
           :position, :mainhand, :uncap_level, :transcendence_step, :element,
           :weapon_key1_id, :weapon_key2_id, :weapon_key3_id,
           :ax_modifier1, :ax_modifier2, :ax_strength1, :ax_strength2,
diff --git a/app/controllers/api/v1/parties_controller.rb b/app/controllers/api/v1/parties_controller.rb
index 272cd19..d8c6ac2 100644
--- a/app/controllers/api/v1/parties_controller.rb
+++ b/app/controllers/api/v1/parties_controller.rb
@@ -142,6 +142,47 @@ module Api
         )
       end
 
+      # Syncs all linked grid items from their collection sources.
+      #
+      # POST /parties/:id/sync_all
+      def sync_all
+        @party = Party.find_by(id: params[:id])
+        return render_not_found_response('party') unless @party
+        return render_unauthorized_response unless authorized_to_edit?
+
+        synced = { characters: 0, weapons: 0, summons: 0, artifacts: 0 }
+
+        ActiveRecord::Base.transaction do
+          @party.characters.where.not(collection_character_id: nil).each do |gc|
+            gc.sync_from_collection!
+            synced[:characters] += 1
+          end
+
+          @party.weapons.where.not(collection_weapon_id: nil).each do |gw|
+            gw.sync_from_collection!
+            synced[:weapons] += 1
+          end
+
+          @party.summons.where.not(collection_summon_id: nil).each do |gs|
+            gs.sync_from_collection!
+            synced[:summons] += 1
+          end
+
+          GridArtifact.joins(:grid_character)
+                      .where(grid_characters: { party_id: @party.id })
+                      .where.not(collection_artifact_id: nil)
+                      .each do |ga|
+            ga.sync_from_collection!
+            synced[:artifacts] += 1
+          end
+        end
+
+        render json: {
+          party: PartyBlueprint.render_as_hash(@party.reload, view: :full),
+          synced: synced
+        }, status: :ok
+      end
+
       # Lists parties based on query parameters.
       def index
         query = build_filtered_query(build_common_base_query)
diff --git a/config/routes.rb b/config/routes.rb
index 983a7ae..48e1015 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -119,7 +119,17 @@ Rails.application.routes.draw do
     end
 
     # Grid artifacts
-    resources :grid_artifacts, only: %i[create update destroy]
+    resources :grid_artifacts, only: %i[create update destroy] do
+      member do
+        post :sync
+      end
+    end
+
+    # Sync endpoints for grid items
+    post 'grid_characters/:id/sync', to: 'grid_characters#sync'
+    post 'grid_weapons/:id/sync', to: 'grid_weapons#sync'
+    post 'grid_summons/:id/sync', to: 'grid_summons#sync'
+    post 'parties/:id/sync_all', to: 'parties#sync_all'
 
     # Grid endpoints - new prefixed versions
     post 'grid_characters/resolve', to: 'grid_characters#resolve'