Adding to the unknown, both Cullen and Tone-Fitzpatrick are returning to the competition after sitting out this season - Cullen with a serious knee injury from which she is still recovering.
Tone-Fitzpatrick's inclusion in the Mystics line-up comes after a stand-out showing for Netball North at the under-23 national champs in Dunedin last month.
The 1.88m defender was reportedly looking fit and strong, and was close to replicating the type of form that saw her selected in the Silver Ferns as a 19-year-old.
Tone-Fitzpatrick played one test in late 2011, when the team was in re-building mode following the World Cup in Singapore, but her career stalled the following year after joining the Magic. The powerful defender, who has been likened to former Silver Fern Linda Vagana, struggled to get any court time behind Casey Kopua and Leana de Bruin and her motivation suffered.
Her confidence returned after linking up with the Steel in 2013, with Tone-Fitzpatrick featuring in every game for the franchise that season - while she was carrying twins as it later turned out.
The pregnancy ruled her out of the New Zealand under-21 side's World Youth Cup campaign last August.
The Mystics are close to finalising their roster for next season, with just one spot left at each end of the court to fill before the August 22 deadline.