Now then, the Explorer's Bone will mete out 4 shrooms, 2 blooms, 2 bears and 1 scary dragonshroom. The Dragonshroom is at a pricey Level 22, so your characters' levels should be at 45 or higher. Definitely, I'm hoping they're at 50 or more already.
You're a gamer, so you can understand why grinding is important, especially at a time like this so if you haven't yet - grind my friend, grind. At this point, going back to camp will give you the chance to recruit a MonyaMonya. Say yes. You might find him useful you'll never know.
Onwards to the Cave of Ruins will have you confronting 4 jacko lanterns and 1 siren (or is she more apt to be a mermaid?) The Breath of Death is basically the same, with only two more jacko lanterns this time but basically all the same monsters that you faced off with previously.
The next map will be the one with the Level 100 enemy (and the reason for the special ending) that I've been talking about for a while now. If you've been following what I'm saying, your characters are basically at levels 50 or higher by now. This will be a little difficult as the creature can heal. Braveheart will be a useful buff at this point, while group attacks and healing is totally crucial. Make sure you've got a game saved before attempting this area.