Well with 650 int on your monster that gives you a fairly good chance to get the item but more intelligence would definitely be a plus. Got the item for the first time today after one reload so it seems to depend on luck of the draw and your monster. I was using an Undine with around 820 int.
That being said if you use the Gameshark and get the mask it should unlock the monster for you once you use it in combining. Go out there and make a Joker. They are pretty darn cool.