When you purchase this key, you get to choose which of the items you want. This is not luck based.

In the server, you can choose one of these:

FLAME AURA
FROST AURA
VOID AURA
ANGELIC AURA
HEART AURA
DRAGON AURA
HISTORY AURA
LIMITLESS AURA
THUNDER AURA
FIEND AURA
WARDEN AURA
CHERRY AURA
GALACTIC AURA
STORM AURA
ABYSS  AURA