gain life should only occur if target is valid, fixes issue 299

src/magic/card/Essence_Drain.java

@@ -35,9 +35,9 @@ public class Essence_Drain {
                 public void doAction(final MagicTarget target) {
                     final MagicDamage damage=new MagicDamage(event.getSource(),target,3,false);
                     game.doAction(new MagicDealDamageAction(damage));
+                    game.doAction(new MagicChangeLifeAction(event.getPlayer(),3));
                 }
             });
-            game.doAction(new MagicChangeLifeAction(event.getPlayer(),3));
         }
     };
 }