emit various sonic frequencies by altering the sounds sent through her vocal chords, allowing her to fly, create energy lances, shatter or disintegrate solid objects, deflect incoming projectiles, eavesdrop on distance sounds, create a masking field that prevents sound from entering or exit a certain area, or send others into a trance, render them unconscious, cause hallucinatory fits, hypnotically control their minds or make them experience intense adoration for her
Siryn's middle name was revealed in X-Force (1st series) #91.
Theresa was reincarnated as a mythical entity known as the Morrigan in X-Factor (1st series) #244. She continued to exist, but as part of a Celtic goddess. However, Siryn was recently seen among the resurrected mutants of Krakoa in House of X #6. Whether or not this means two versions of Theresa Cassidy currently exist is uncertain.