Prior to the start of the series, the Doctor sent out the confession dial to Missy, believing that when he faced Davros once again, he would die. We learned - or were told - that it contained his last will and testament but we suspect there was far more to it than that. And its appearance in Fear The Raven as Ashildr forced the Doctor to hand it over, only re-established its importance. But what is it? What secret is the Doctor hiding? Or is it just a means to obtain the Doctor's name, calling back the Time Lords and restarting the Time War? All we know is that it will be significant to the final two episodes; perhaps it is this series' fob watch, an artefact that will have huge importance to this particular story's end game?