CRYSTAL

Found In Northwest Castle
Matoya's CRYSTAL was stolen by ASTOS, and is retrieved after you defeat him in the Northwest Castle. Return it to Matoya to earn the HERB which in turn lets you get the mystic KEY.
Compare CRYSTAL to other Items
Treasures: Containing CRYSTAL – 1 shown
Map
The specifics of where this treasure can be found
Notes
Northwest Castle Obtained after defeating ASTOS
HERB RUBY

Related

Across the Bridge

The SHIP
Page 1
With GARLAND defeated, the King erects a bridge leading to Pravoka and Matoya's Cave.

Gathering Clues (Optional)

The CROWN and the Mystic KEY
Page 2
Travel to the Dwarf Cave and the Northwest Castle to determine your next course of action.

Battle with ASTOS

The CROWN and the Mystic KEY
Page 4
The King of the Northwest Castle reveals himself to be ASTOS, who has the CRYSTAL you need.

The Mystic KEY

The CROWN and the Mystic KEY
Page 5
Trade the CRYSTAL for the HERB and use it to revive the Elf Prince and finally obtain the mystic KEY.

Crystal Eye

Mystical orb made of crystal.
Found In Western Keep
Matoya's Crystal Eye was stolen by Astos, and is retrieved after you defeat him in the Western Keep. Return it to Matoya to earn the Jolt Tonic which in turn lets you get the Mystic Key.