I am not posting the pictures as they are very spoilerish but here are some clues as to the possible reason for the regeneration of the Tenth Doctor. I will let you guess, two people from the Tenth Doctor's era may have vengeance on their minds. One might be obvious but the other one not so much. It is rumoured that they will team up against the Doctor.
clues.
1. ring
2. Human Nature/Family of Blood
3. The journal of Impossible things
You can look here if you want to find out more including the much speculated return of Rose for the finale.
