Add Roaming Ghostlight

Fixes #75

lib/magic/card.rb

@@ -55,6 +55,15 @@ def keywords(*keywords)
       def protections(*protections)
         const_set(:PROTECTIONS, *protections)
       end
+
+      def enters_the_battlefield(&block)
+        etb = Class.new(TriggeredAbility::EnterTheBattlefield)
+        etb.define_method(:perform, &block)
+
+        define_method(:etb_triggers) do
+          [etb]
+        end
+      end
     end
 
     def initialize(game: Game.new, owner:)

lib/magic/card_list.rb

@@ -53,6 +53,10 @@ def by_any_type(*types)
     end
     alias_method :by_type, :by_any_type
 
+    def excluding_type(*types)
+      reject { |c| c.any_type?(*types) }
+    end
+
     def except(target)
       self.class.new(reject { |c| c == target })
     end

lib/magic/cards/roaming_ghostlight.rb

@@ -0,0 +1,16 @@
+module Magic
+  module Cards
+    RoamingGhostlight = Creature("Roaming Ghostlight") do
+      cost generic: 3, blue: 2
+      type "Creature -- Spirit"
+      power 3
+      toughness 2
+      keywords :flying
+
+      enters_the_battlefield do
+        choices = game.battlefield.creatures.excluding_type(T::Creatures['Spirit'])
+        game.add_effect(Effects::ReturnToOwnersHand.new(source: self, choices: choices))
+      end
+    end
+  end
+end

spec/cards/roaming_ghostlight_spec.rb

@@ -0,0 +1,17 @@
+require 'spec_helper'
+
+RSpec.describe Magic::Cards::RoamingGhostlight do
+  include_context "two player game"
+
+  before do
+    ResolvePermanent("Wood Elves", owner: p2)
+  end
+
+  context "when it enters the battlefield" do
+    it "returns non-Spirit creature to its owner's hand" do
+      ResolvePermanent("Roaming Ghostlight", owner: p1)
+
+      expect(p2.hand.by_name("Wood Elves").count).to eq(1)
+    end
+  end
+end