With Master Tristan's help, you follow Tornix/Trinicus into the Mausoleum.
Explore the Mausoleum
Follow the path until you reach a hallway with doors. Don't try to open the double door in this hallway yet, because it is locked. Go into each of the smaller doors and open the sarcophagus to fight a monster. You get an item after each battle. From left to right, you will get a Protect Ring, Spy Lens/Magic Lens, Hourglass, Chain Mail, and Rune Bottle. Be sure to equip the Chain Mail.
Go down the stairs at the rightmost side of that hallway, and keep going until the path splits (it's hard to see, but the notch in the wall below is a door). Go downward to the next room, and get the two chests in this room. The lower one is an Apple Gummy/Apple Gel/Apple Gummi and the upper one is a Creamy Cheese. Go back to where the path splits and use the door to the right.
First, if you didn't get the Knight's Sabre/Saber or a Sabre/Saber from the merchant, or if you just want an extra Sabre/Saber, go north to get it. Then go south until you can go to the right, and go through the north door.
In the room with the five statues, check the following statue:
x x x O x
This will make two chests appear in the previous room, but before you go back there, go through the double door to the right to find a chest that contains a Chain Mail. Then go back the way you came and open the two chests. The one on the right contains a Sage, and the one on the left contains a Mixed Gummy/Melange Gel. Go south until you reach the next area.
Go to the right and open the chest to get a Cheese/Fresh Milk. Use the save point, then check the statue above you. You will have to fight a Golem. Don't use Psion Bolt/Demonic Blade/Demon Fang on it, because those abilities will heal it.
After you defeat the Golem, move the statue downward through the room, then to the left. Put it on the brown tile. Go through the door that you just opened, open the chest to get the Lace Ruby, then exit the room.
Keep going east, and go through the double door behind the statues to find three chests. From left to right, they contain Creamy Cheese, an Orange Gummy/Orange Gel/Orange Gummi, and a Remedy Bottle.
Your next destination is the hallway with locked double doors. To get there, exit the room where you opened the three chests, then go west, then north up the hallway and through the door behind the statue. Then go west and south through the door, then go west and north through the door. Follow the path from here until you are in the hallway with the doors that led to the sarcophagi, and go through the double doors.
Step on the star symbol to be transported to a new area.
Walk onto the moving platform that stops just above you. When it stops, walk left and pull the lever. Go to the right, but this time use the platform that stops above you to reach a couple of chests. The left one contains a Rabbit's Foot, and the one on the right contains Cheese. Then use the platforms to go back to the platform with the star symbol, but don't step on the star symbol yet.
Stand to the left of the star symbol and another platform will eventually arrive, but it might take a while. It takes you to another chest, which contains a Reverse Doll.
Now use the platform that stops to the right of the star symbol. Go down the stairs and try to pick up the Lace Ruby. If you have Jet Boots, equip them on someone if you haven't already. Then go up the stairs and step on the diamond symbol. You will start floating temporarily, and there will be some dialogue. When the moving platform is approaching, step on the diamond symbol again to make sure that you keep floating for a while, then run onto the platform. When you are near the star symbol again, run left and down, and go down the stairs to an area with an electrified floor. If you are still floating, you won't take damage. Go left and down to get the Lace Ruby. Run down and right from where the Ruby was to find a chest (Lavender), then run back up the stairs.
Go to the right of the star symbol and use the southern moving platform, then go through the double doors.
Use the save point and heal up. There will soon be a boss battle. You will not be attacked in the room with the save point, so fill your food sack and keep walking around until everyone is healed up. Change Mint's tactic to Value HP over TP, and have Chester Go Berserk. If Cless/Cress knows the Lightning Bolt skill, equip it.
Go north from the save point and you will be attacked by two Golems. Don't use Psion Bolt/Demonic Blade/Demon Fang, because that heals the monsters. Use Lightning if you have it.
Once the battle is over, follow the path and you will find Tornix/Trinicus. Watch the cutscene that follows, where you arrive in an unfamiliar place.