Save the game after clearing it to access a new dungeon.

The small letters on mana egg combinations define something that affects your characters:

• R - Adds range to spells.
• MP - MP cost of the spell is decreased.
• P - Spell potency is increased.
• H - Spells that affect targets several times will affect them several times more.
• W - Area effect spells get a wider range.
• S - The time to charge a spell is decreased.
• IP - The spell deals more IP damage.

Just like the Test0 in Final Fantasy VII, there is a weak enemy in the game that gives a lot of experience. It's called a Lucky Mink and it can only be found on levels 11 to 14 in the Starry Corridor.

You will want to have spells to incapacitate the monster and spells with very large, very wide area effects since the creature is hard to hit (high Agility). Good luck!