Use etb DSL for Acidic Slime

lib/magic/cards/acidic_slime.rb

@@ -6,25 +6,20 @@ module Cards
       keywords :deathtouch
       power 2
       toughness 2
-    end
-
-    class AcidicSlime < Creature
-      def target_choices(_)
-        game.battlefield.cards.by_any_type("Artifact", "Enchantment", "Land")
-      end
 
-      class ETB < TriggeredAbility::EnterTheBattlefield
-        def perform
-
-          effect = Effects::DestroyTarget.new(
+      enters_the_battlefield do
+        effect = Effects::DestroyTarget.new(
             source: permanent,
           )
-          game.add_effect(effect)
-        end
+        game.add_effect(effect)
       end
 
-      def etb_triggers = [ETB]
+    end
 
+    class AcidicSlime < Creature
+      def target_choices(_)
+        game.battlefield.cards.by_any_type("Artifact", "Enchantment", "Land")
+      end
     end
   end
 end