In Crimson Seas you obtain maps to new distant lands beyond the borders of Valeria, allowing you to import trade goods from Araby to increase your victory points, purchase Tomes of great power to increase your resource production, rescue captured nobles from the villainous Amarynth Empire and plunder the wealth of the Cursed Isle. Beware of the monsters of the sea, however, as they grow in power and wreak havoc throughout Valeria.

Along the top of the playing field is a new game board called "The Islands". To access the islands you must use a new action called "Sail" and to sail you must spend one map token, then you can access Araby to get goods, Nae Aerie to get Tomes, Exekratys to get lost to retrieve resources, and Amarynth to rescue the captured Noble's.

This expansion has new icons, new tokens, new mechanics, new card types, and new cards for all existing card types.