diff --git a/lib/director.rb b/lib/director.rb
index e8d7aa7..a34ec47 100644
--- a/lib/director.rb
+++ b/lib/director.rb
@@ -107,7 +107,7 @@ class IMICRTS
 
     def spawn_entity(player_id:, name:, position:)
       _player = player(player_id)
-      _player.entities << Entity.new(
+      ent = Entity.new(
                 name: name,
                 director: self,
                 player: _player,
@@ -115,6 +115,9 @@ class IMICRTS
                 position: position,
                 angle: 0
               )
+      _player.entities << ent
+
+      return ent
     end
 
 
diff --git a/lib/entities/buildings/power_plant.rb b/lib/entities/buildings/power_plant.rb
index bb0f30f..eb5b599 100644
--- a/lib/entities/buildings/power_plant.rb
+++ b/lib/entities/buildings/power_plant.rb
@@ -1,6 +1,6 @@
 tiles = [
   [false, false, false, false, false],
-  [false, false, false, false, false],
+  [false, false, true,  false, false],
   [false, false, true,  false, false],
   [false, false, true,  false, false],
   [false, false, true,  false, false],
diff --git a/lib/tools/place_entity.rb b/lib/tools/place_entity.rb
index cefaf68..fd56f43 100644
--- a/lib/tools/place_entity.rb
+++ b/lib/tools/place_entity.rb
@@ -10,7 +10,22 @@ class IMICRTS
     end
 
     def draw
-      # TODO: draw affected tiles
+      each_tile(vector_to_grid(@game.window.mouse)) do |x, y, tile|
+        if tile.entity || tile.type != :ground || @director.map.ore_at(x, y) # tile unavailable
+          Gosu.draw_rect(
+            tile.position.x + 2, tile.position.y + 2,
+            @director.map.tile_size - 4, @director.map.tile_size - 4,
+            Gosu::Color.rgba(200, 50, 50, 200), ZOrder::OVERLAY
+          )
+        else # tile available
+          Gosu.draw_rect(
+            tile.position.x + 2, tile.position.y + 2,
+            @director.map.tile_size - 4, @director.map.tile_size - 4,
+            Gosu::Color.rgba(100, 100, 100, 200), ZOrder::OVERLAY
+          )
+        end
+      end
+
       @preview.draw
     end
 
@@ -18,9 +33,10 @@ class IMICRTS
       # TODO: ensure that construction worker is alive
       cancel_tool if @construction_worker.die?
       vector = vector_to_grid(@game.window.mouse)
+
       if tile = @director.map.tile_at(vector.x, vector.y)
         position = tile.position.clone
-        @preview.position = position
+        @preview.position = position + @director.map.tile_size / 2
         @preview.position.z = ZOrder::OVERLAY
       else
         @preview.position.z = -10
@@ -34,16 +50,60 @@ class IMICRTS
 
       tile = @director.map.tile_at(vector.x, vector.y)
       return unless tile
-      position = tile.position.clone
+      position = tile.position + @director.map.tile_size / 2
 
-      @director.spawn_entity(
+      ent = @director.spawn_entity(
         player_id: @player.id, name: @entity,
         position: CyberarmEngine::Vector.new(position.x, position.y, ZOrder::BUILDING)
       )
 
+      each_tile(vector) do |x, y, tile|
+        tile.entity = ent
+      end
+
       cancel_tool
     end
 
+    def can_use?(vector)
+      return false if @game.sidebar.hit?(@game.window.mouse_x, @game.window.mouse_y)
+      useable = true
+      done  = false
+
+      if tile = @director.map.tile_at(vector.x, vector.y)
+        ent = Entity.get(@entity)
+        origin = (tile.grid_position - 2)
+
+        each_tile(vector) do |x, y, tile|
+          if tile.entity || tile.type != :ground || @director.map.ore_at(x, y)
+            useable = false
+            break
+          end
+        end
+
+        return useable
+      else
+        return false
+      end
+    end
+
+    def each_tile(vector, &block)
+      if tile = @director.map.tile_at(vector.x, vector.y)
+        ent = Entity.get(@entity)
+        origin = (tile.grid_position - 2)
+
+        ent.tiles.each_with_index do |array, y|
+          array.each_with_index do |space_required, x|
+            next unless space_required
+
+            other_tile = @director.map.tile_at(origin.x + x, origin.y + y)
+            if other_tile
+              block.call(origin.x + x, origin.y + y, other_tile)
+            end
+          end
+        end
+      end
+    end
+
     def button_down(id)
       case id
       when Gosu::MsRight
@@ -54,7 +114,7 @@ class IMICRTS
     def button_up(id)
       case id
       when Gosu::MsLeft
-        use_tool(vector_to_grid(@game.window.mouse))
+        use_tool(vector_to_grid(@game.window.mouse)) if can_use?(vector_to_grid(@game.window.mouse))
       end
     end
   end