You can link your KING's RAID account to 4 different types of SNS accounts: Facebook, Google, Game Center, and Apple.

On Android devices, you can login/link with a Facebook or Google account. 

On iOS devices, you can login/link with a Facebook, Game Center or Apple account.

To link your account, go to [Misc. Menu] > [Game Settings] > [Others] and select one of the SNS accounts shown right below your Game ID.

Please note that if the button is disabled with the text 'Connected', it means that it's already connected to your account. If a pop-up with the text 'The selected SNS account has already been linked to another King's Raid account.' appears on your screen, this means that the SNS account you've selected is already linked to another KING's RAID account.