After fighting Dhaos's forces on land and in the air, it is time to face Dhaos himself.
You will automatically be healed up after the aerial battle. Buy more supplies. Make sure that Cless/Cress is equipped with a weapon now that the Gungnir is gone.
When you are ready, go north to the Valhalla Plains. To get a new skill for Cless/Cress, from the entrance go north twice, east twice, south, east twice, and north. You can get the skill later if you can't afford it now.
From there, to reach Dhaos's castle, go east twice, north twice, west twice, north twice, east three times, north, and east twice.
Cross the bridge and go north to reach the castle. Cless/Cress should use Lightning against the enemies here. Make sure that Cless/Cress has a non-elemental weapon equipped. Have Klarth/Claus ready to summon Luna.
Iron Man: use Indignation.
Vine: use Fire Storm (learned in Dhaos's Castle).
Draygen: use Fire Storm.
Druid: use Fire Storm & Maxwell.
Dullahan: use Ray.
Charon: use Maxwell.
Adept: use Ray.
Draygens occasionally drop ?Weapons, and sometimes the ?Weapon is a Moon Falux. Otherwise, it is just a Longsword. You will want the Moon Falux, but don't equip it now.
Through the Castle
In the first room of the castle, go left. Go into the far left door, open the chest for a Flame Mantle, and exit right to find another chest (Aqua Mantle). Now go down. On the stairs, go right and check the statue for a Mystical Rune. Go down from there, go down the stairs, go slightly right from the stairs, and go up through the door. Go up to reach three weapon stands. Check on all three. From right to left, they contain a ?Weapon that becomes a Slayer Sword, a Mecha-Halberd, and a Halberd. Leave this room and use the exit on the right.
In this room, check the plant to find a Savory and Sage, then exit to the right. Go up and step on the switch, then go through the door that you just opened to get a new spell for Arche (Fire Storm). Then go back out.
Go left, and go up to the weapon stands. Check them for items. From right to left, they are a Halberd and a Mecha-Halberd. Then exit south. Go to the right again, and step on the switch. This will unlock the door on the far left. Go through it.
Follow the path. When you reach the two doors, go through the one on the right. The correct order to step on the buttons is: up, down, right, left, down, up. If you make a mistake, just exit and go back in, or check the sign. When you hear the door open, exit and go through the door on the left. Then go north through the open door.
Go to the right and go up the stairs, go straight up past the column, then go to the right and go up the stairs. At the three doors, go through the left door. There is an Orange Gummy on the left and a Life Bottle on the right. Then go through the door on the right. The bottom left chest contains an Apple Gummy, the bottom-right chest contains a Rune Rod, and the top chest contains an Apple Gummy. Finally, go through the middle door.
Go left first to find some chests. From left to right, they contain an Orange Gummy, a Life Bottle, and an Apple Gummy. Then go back, and go to the right.
In the room with the switches, go up and read the sign first. Then you will have to step on the switches. Try to step on the switch after Arche does.
Use the save point on the way.
When you reach the two doors, go through the bottom one to find some chests. The one on the left contains a Rune Bottle, and the one on the right contains a Protect Ring. Then go back, and go through the top door.
Go through the doors on the left. The top chest contains a Battle Rune and the bottom chest contains a Steak. Then go through the far north door.
Go up the stairs, push the Demitel statue into the hole, then go back downstairs and push the Demitel statue onto the button. Go through the door.
Step on this switch twice and choose someone to stay behind. I recommend Arche. If you want someone else to stand on the switch, talk to whoever is standing on it currently. Go through the door.
Follow the path. When you see the locked door to your right, go left. Go left again, and keep going left, then up the stairs.
Go left, and keep going until you reach two doors. Use the rightmost door to find a save point. Then go back and go through the left door. Then go through north door, and prepare for a mini-boss. Equip Cless/Cress with a Moon Falux if you have one.
Klarth/Claus should use Luna, or, if you have Arche, she should use Indignation. Mint can cast Hammer on the Evil Lord.
Dhaos's Castle, Part 2
Re-equip Cless/Cress with a non-elemental weapon, and get the treasure that was behind the monster. Now exit the room, use the stairs to the southwest, go down the stairs, then keep going to the right until you reach two doors. Go through the unlocked one, and keep going until you reach the person you left behind. Talk to that person and choose to leave nobody behind.
From here, keep going south. Whenever the path splits, go right. Continue going south. Eventually, you reach a room with mirrors. When you check the mirrors, you will fight an Evil Lord and Draygens again, so equip Cless/Cress with the Moon Falux first, and prepare Arche to cast Indignation and Klarth/Claus to cast Luna. Check each mirror and fight each monster, until you are taken to a new room. In the room on the left, the chests contain (from left to right) Lavender, 10000 Gold, Hourglass, Elixir, and White Mist. In the room on the right, the chest contains the spell Distortion. Disable this spell for now. After you get the treasure, exit by checking the mirror.
Now go south down the stairs and check the nearest mirror to fight another mini-boss. After you are transported, walk left, check both gargoyles to make a chest appear (Mental Ring), then open the other chests. From left to right, they contain a Magical Broom, Rune Bottle, and Armlet. Equip the Magical Broom on Arche now.
Go to the right past the mirror, and go down. Follow the path and you will reach a room with four switches. Press them in this order: up, down, left, right, down, up. After you do it correctly, exit the room to find a chest that contains a Gold Key.
Go back to the mirror and through it, then go up the stairs to the right, past the column, and go up the stairs to the right, go through the middle door, go through the upper right door, go up past the table, go up the stairs, go through the upper door, go through the northernmost door, and go straight up into the room with the switch that someone has to stand on.
Step on the switch and leave Arche behind. Go through the door, go up the stairs, and go down through the door. Now check the door on the right to unlock it, and go through.
Walk to the right, and Arche will come join you. Open the chest to get a Charm Bottle, and go back, out to the hall, and exit to the left. Use the south exit. Unlock the door to the left and go through to find some items. The bottom-left chest contains a Dragon Steak, the bottom-right chest contains a Silver Cape, and the chest on top both contain Dragon Steaks.
Exit and go through the door on the right. Go left, then go up the stairs to the left, then go to the right and down, then through the door on the right. Check the door in this room, and the four of you will unlock it.
Go through, and prepare for another mini-boss fight with an Evil Lord and Draygens. After the battle, go back to the save point and save the game, because Dhaos is next.
You will not be attacked in Dhaos's room, so you can walk around to heal up with the food in your sack.
Replenish TP. Use Mixed Gummies if you have to.
Change Klarth/Claus and Arche's tactics to not cast spells. It will be better to cast their spells manually. Set Mint to Value HP over TP. Make sure that Arche is equipped with a Mystical Rune, and if you have more Mystical Runes, equip one on Mint, and if you have one left, one on Klarth/Claus. Set Cless/Cress to use Tempest and Blade Storm. Blade Storm won't hurt Dhaos, most likely, but it does have a good chance of stunning him, which will keep him from casting any spells for a short time. Set your formation with everybody all the way on the left of the screen, with Cless/Cress on the far right.
Dhaos will not attack very often if the Evil Lords are still alive. However, you will have to occasionally attack the Evil Lords to prevent them from killing you.
Have Arche cast Lightning or Ice Needle on Dhaos. These are weak spells, but they only take a short amount of time to cast, so they have a good chance of interrupting most of Dhaos's spells.
Klarth/Claus should constantly attack Dhaos with Luna.
Have Cless/Cress constantly attack Dhaos with Blade Storm in the hope of stunning him.
After the Evil Lords are both gone, Mint should cast Hammer on Dhaos repeatedly.