The fourth expansion for Heart of Crown. It requires either the base set or the Fairy Garden expansion to play. This expansion adds a completely new type of card, Support Cards, which confer an extra bonus when nominating a Princess. A new Rare card is also introduced, Oasis City Nefertiri, which does not enter the market like normal. The set also introduces a new variety of Curse card. Additionally, new rules are added for games with 8 or more Princesses available.

Six City Alliance Includes; 102 Cards,16 Randomizer Cards, 17 Dividers and a Rulebook. These 102 new cards are composed of 1 new Princess (Oasis Princess Emshiele), 1 Oasis City Nefertili card (used with Princess Emshiele), 16 new Common Cards and 20 Misfortune Cards.

The Contraband and Conquest Tokens included in the Fairy Garden Base Game will be used for both Oasis Princess Emshiele's ability and the Conquest Card abilities included in Six City Alliance.