Shinnok's fall from grace was caused by his lust for power and more specifically, his desire to take Earthrealm for himself. At the dawn of time, when the realms were created, Shinnok desired to rule Earthrealm, and thus acquire for himself immense power. However, Shinnok couldn't enter Earthrealm without the Elder Gods being aware of his actions. To resolve this issue without directly defying the sacred rules, Shinnok created a powerful amulet, weakened the dimensional barriers, and entered Earthrealm. During the war against his fellow gods, he came into direct conflict with the thunder god Raiden.