Final Chapter: Light(part 1)
Make sure your units have some space in their inventory so they can get the level S weapons because Merlinus will not be with you. Also be perpaired with healing staffs, physic, fortify, and restore are recommanded.
Also, use any stat changing items you have, this is the last chapter, so if you don't use it now, they are useless.
This is a hard chapter. You'll have to fight 6 previous bosses again, and they are all at level 20 with level S weapons. The good thing is they won't come to you all at once.
First, the door to Uhai's room will open, he uses bow, so attack him in close range, make sure to finish him off, or if you can't finish him off, make sure the units close to him don't die due to his attack in the enemy phase.
Next is Kenneth's room. there are 3 units in that room, but 2 of them won't bother you for now, one will attack with Bolting, so get out your long range magic tomes and get ride of him fast, or protect anyone who's weak against magic like Nils.
Then Brendan's door will open. He's a worrior with an axe, so let magic users attack or use two ranged weapons. If you stayed at the lower part of the map, it'll take one turn for them to get to your units.
Next is Darin'd door. He has tones of defense, so bring out your magic users.
Second to the last is Ursula's room. She has low defense, so attack with melee weapons. But make sure the attacker can withstand some magic counter attack.
The last room has Lloyd and Linus. They are pertty weak compair to the others in this chapter. Also by now you should have most of the level S weapon, so they won't be a problem.
After you are finished with all of them, the door to the main room where Nergal is will open. Attack with all you got and victory is yours.