Shada D'ukal was a mercenary whose outward appearance belied her deadly profession. She hailed from a secretive, all-female military order known as the Mistryl Shadow Guard.
Shada's family included multiple uncles. She enlisted in the Shadow Guard during 3 BBY. By 0 BBY, Shada belonged to a six-member Shadow Guard squad, commanded by Manda D'ulin. The scientists involved with the Hammertong project recruited them to protect a prototype of the second Death Star's superlaser. Following a disastrous turn of events during this mission, Shada, along with her close friend and fellow guard Karoly D'ulin, commandeered the Strike Cruiser assigned to transport the prototype. They fled to Tatooine and adopted the identities of the Tonnika sisters, hoping to secure a freighter to assist in returning a portion of the device to Emberlene.
Around 8 ABY, Shada journeyed through the galaxy on the freighter The Fury with Mistryl apprentice Dunc T'racen. The two became entangled in an intricate scheme orchestrated by Ghitsa Dogder and Fenig Nabon. Subsequently, Shada took on the role of bodyguard for smuggler leader Mazzic. In this capacity, she typically sported plaited hair and maintained an impassive demeanor – until danger arose. At that point, she became intensely focused, employing enameled zenji needles with deadly precision and utilizing her formidable combat skills to safeguard the smuggler chief.
She attended the meeting on Trogan, where she defended Mazzic, and later participated in the gathering on Hijarna, contributing to the formation of the Smugglers' Alliance.
During 19 ABY, Shada intervened to prevent Karoly from assassinating Mazzic, which resulted in punishment from the Eleven, the leaders of the Mistryl. To evade the Mistryl hunter teams, she left Mazzic's service, seeking to join the New Republic. Instead, Leia Organa Solo offered Shada's expertise to Talon Karrde, who was heading into the Kathol sector in order to find a copy of the Caamas Document. Shada accompanied him, and they developed a close relationship. When Karrde uncovered information exposing the truth about the false Grand Admiral Thrawn, Shada prevented the cloned Major Grodin Tierce from murdering Gilad Pellaeon and a Mistryl leader, Paloma D'asima. As a consequence, the hunter teams were recalled, and Shada formally joined Karrde's newly established joint intelligence organization, assuming the role of Karrde's informal second in command, a position vacant since Mara Jade departed.
Throughout the Yuuzhan Vong War, Shada remained Karrde's trusted lieutenant and business associate. She played a role in transporting Jedi Initiates from Yavin 4 to Coruscant. Rumors circulated that she had shared details about the Hammertong device with Karrde, which enabled Booster Terrik to install a superlaser on board the Errant Venture.
Christine Hewett, a model, portrayed Shada D'ukal disguised as Brea Tonnika. The short story "You Owe Me a Ride" revealed that Karoly and Shada are, in fact, Brea and Senni Tonnika within the canon Star Wars continuity.