Stronghold Kingdoms – Kingmaker Bundle Digital Download CD Key

Go here to Create a new Stronghold Kingdoms account and download Stronghold Kingdoms or log into an already existing account.
Click on 'Account Details'
Scroll down to the section ‘Offer Codes'
Paste the code into the 'Redeem Code’ box and hit enter
Find your prizes in-game in the ‘Card Packs’ and ‘Premium Tokens’ sections of the card screen (icon on the top)