Wyvern Egg

Found In Castle Deist 2F
The dying Wyvern in Castle Deist will give you the last Wyvern Egg, which you'll have to incubate deep in the Deist Cavern. Doing so allows you to gain a Wyvern later in the game, which is pretty cool.
Compare Wyvern Egg to other Key Items
Treasures: Containing Wyvern Egg – 1 shown
The map where the treasure is found
Map
The specifics of where this treasure can be found
Notes
The monsters guarding this treasure, which will attack when the treasure is opened
Guarded By
Castle Deist 2F Given by wyvern if you have the pendant -
Pendant White Mask

Related

Deist Cavern

The Dragoons of Deist
Page 4
Fulfilling a dying wish, the party brings the Wyvern Egg deep into the Deist Cavern.

Hilda Gone Mad?

Princess Hilda
Page 1
Princess Hilda has reportedly been acting strangely since being rescued from the Dreadnought.