Nala initiated new members of the order into the mysteries of Tiamat, all the while claiming that it was really Bahamut's power she was channeling. Tiamat's power gave members of the order the ability to use their breath weapons more often than normal and the order used this ability to great effect in combat. Because the dragonborn were unfamiliar with the gods of Toril, they did not realize they were calling on Tiamat's power rather than Bahamut's.
The warrior Balasar infiltrated the Platinum Cadre and was able to find evidence that proved Nala was a worshiper of Tiamat. Nala fled to the Black Ash Plain when her secret was revealed and joined Skuthosiin's army. She was killed by Balasar in the battle at Ashhold.