As the Rafiq of Jerusalem, Kadar assigned at least one Assassin agent to the court of the King of Jerusalem to serve as a spy. When the Templar leader Basilisk arrived, garrisoning his troops in the city, Kadar was in position to gather intelligence on him as well.
In this capacity, he was contacted by fellow Assassin Altaïr Ibn-La'Ahad in 1190, hoping to obtain the last key to the Temple of Sand in his quest for the Chalice. This key had been reported by a captive old man at the Templar Hospital in Tyre to be in the possession of Basilisk. Kadar revealed to Altaïr that under normal circumstances, reaching Basilisk would necessitate entering the King's palace, as the Templar accompanied the king at all times. Infiltration of the palace would be an immense feat, but fortunately for Altaïr, the King was hosting a party outside the palace, giving a chance for the Assassin to catch Basilisk without having to deal with the castle's defenses. Without this party's exact location on hand, Kadar sent Altaïr to eavesdrop on the nobility at the city gardens. Before the Assassin departed, the Rafiq asked him to investigate the status of his spy, whom he had lost contact with since Basilisk's arrival.
True to Kadar's advice, Altaïr was able to discover the location of the event at Lacoeur's villa through gossip in the gardens and a noble named Ayman. When he launched an assault on the party, he chanced upon Kadar's missing spy as well, who reassured him that his identity remained secret, only that the vigilance of Basilisk had permitted no chance for messages. By the end of his attack, thanks to the spy, Altaïr was successful in infiltrating the villa's keep and stealing the last key from Basilisk.