On Mt. Palo, there is a creature named Devil, who you must defeat to rescue the kidnapped children. Since Devil can be a pain sometimes, you may want to use this. Recruit a Tanki, because he is very good at recruiting other monsters. Recruit some rare creatures while walking around on Mt. Palo and then go face Devil. You want to attack him, DO NOT USE MAGIC, he is not the least bit vulnerable to it. Have a full party of your best monsters and have good defenses, if you want to beat him.