** Possible spoilers and speculation ahead **
After King Tommen forbade trials by combat in the eighth episode of Game of Thrones season 6, it looked like the High Sparrow had finally managed to defeat Cersei Lannister. But it turns out she may have another way of getting out of this mess as was evident from this conversation between her and Qyburn:
Qyburn: Your grace, that old rumor you told me about—my Little Birds investigated.
Cersei: Tell me. Was it a rumor or something more?
Qyburn: More, Your Grace. So much more.
As expected, fans have already begun decrypting this secret exchange between the two and many believe that Qyburn was referring to the wildfire cache hidden by the Mad King, somewhere in King’s Landing. The theory suggests that Cersei is on her way to become the Mad Queen as she had already threatened to burn the city multiple times and with everyone against her at the moment, she may decide to ‘burn them all’, just like Aerys Targaryen.
Bran’s visions [below] as well as Tyrion’s quote [above] about Mad King and wildfire are also believed to be a foreshadowing of the events to come. Also, in an interview The High Sparrow actor Jonathan Pryce revealed that something unpleasant is about to happen during Cersei’s trial. Click here to read what he said.