Xenogears Tips

Defeating Dues (First battle)
This battle may seem impossible since every time you attack him, he heals 16000 HP. However, there is a simple solution.

Most of the time he will do an attack that halves the HP of everyone. By everyone I mean him as well. He starts off with 40000 HP, so it only takes 4 of these moves for him to fall down to 2500HP. This is where you attack him with a deathblow that deals over 2500HP damage.

I suggest unleashing ID for 3 rounds and using one of those attacks.