To me, and I would need to go back and check the solicitations, but it appears they keep changing what Issue the new hero who is supposed to get their own book will be in.
In Spawn #280, we get Cyan mentioning the Black Mirror.
Now, the solicitation for Spawn #281, out tomorrow, states:
A NEW HERO PREMIERES! Look for this exciting new character as she makes her heroic debut. Only ONE ISSUE left until the thrilling conclusion of ‘DARK HORROR!’
Is this the hero we were promised?