Add Titanic Growth

Fixes #221

lib/magic/cards/titanic_growth.rb

@@ -0,0 +1,16 @@
+module Magic
+  module Cards
+    class TitanicGrowth < Instant
+      card_name "Titanic Growth"
+      cost generic: 1, green: 1
+
+      def target_choices
+        creatures
+      end
+
+      def resolve!(target:)
+        trigger_effect(:modify_power_toughness, power: 4, toughness: 4, target: target, until_eot: true)
+      end
+    end
+  end
+end

lib/magic/effects/apply_power_toughness_modification.rb

@@ -3,9 +3,10 @@ module Effects
     class ApplyPowerToughnessModification < TargetedEffect
       attr_reader :power, :toughness
 
-      def initialize(power: 0, toughness: 0, **args)
+      def initialize(power: 0, toughness: 0, until_eot: true, **args)
         @power = power
         @toughness = toughness
+        @until_eot = until_eot
         super(**args)
       end
 

spec/cards/titanic_growth_spec.rb

@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+RSpec.describe Magic::Cards::TitanicGrowth do
+  include_context "two player game"
+  let!(:wood_elves) { ResolvePermanent("Wood Elves") }
+
+  it "gets +4/+4 until end of turn" do
+    p1.add_mana(green: 2)
+    p1.cast(card: Card("Titanic Growth")) do
+      _1.pay_mana(green: 1, generic: { green: 1 })
+      _1.targeting(wood_elves)
+    end
+
+    game.tick!
+
+    expect(wood_elves.power).to eq(5)
+    expect(wood_elves.toughness).to eq(5)
+  end
+end