New Ancient Ganadors have been added to this expansion for you to challenge. To unlock them, follow the Atlantis story questline, starting with the quest Land of the Legendary King (Stockholm, see Chapter 1: King Minos information page for details). After completing that quest, take the quest Egypt and Atlantis (Requires English and 10k+ Adventure Fame) from the London Adventurers' Guild.
Once you have completed the quest, go back to your home nation's capital and the Port Official will talk to you about Ancient Ganador. Take Ganador Transport to the mission headquarters and talk to the Spy. He will ask you to investigate a rumor. Accept his request to start your first Ancient Ganador Mission.
This time, the opponents will be fairly easy, so you should be able to defeat them by yourself even if Battle is not your specialty.
In the future, when you talk to the spy, he will randomly mention a certain Ganador has seen strange apparitions. Challenge and defeat that Ganador, then repeatedly talking to the Spy and click on the Ganador Mission Info should randomly get you the message for another Ancient Ganador. From now on, Ancient Ganadors can be quite difficult so you are recommended to go with other players and form a fully battle-ready fleet. They will using special Fire Arrows to attack and can do significant direct damage to sailors, so surgery will be quite important.