All class change items in one try:
To get all class change items in one try for your party characters, first acquire at least six "???" seeds. Then, go to any seed bucket at a town inn or the Sanctuary Of Mana, and set the number of seeds to plant at six for "???" seeds. The game will give you one of every class change item for your party. Note: Do not plant the "???" seeds one at a time, or else the item juggle will reset and you may get duplicate class change items.
Secret boss fight:
To fight the secret boss, first complete both the Dark Stone Benevodon dungeon and sub-boss mission of your first main party member (for example, if you chose Duran as you main character, you must complete both Crystal Desert and Dragon's Maw). Then, instead of going to the Sanctuary Of Mana, return to the entrance of the Dark Stone Benevodon's dungeon. Once there, you will now see a statue of a Black Rabite. Examine it to teleport to the sub-boss area again. A warning message about a powerful enemy that lies ahead will appear. Proceed to fight the game's toughest boss, the Black Rabite.