3. Base Under Siege
It's a classic story in the early years of Pat Troughton's time at the TARDIS controls- the base under siege. It made up most of his first two series in the role,and it would be great to have he and Matt Smith,on the basis of 'Cold War',do something similar in future. Go back and watch the awesome foursome of 'The Power Of The Daleks','The Underwater Menace','The Moonbase' and 'The Macra Terror' for further examples. Plus of course, it would be churlish to forget 'The Ice Warriors',the introduction for the chilly Martian invaders who'd pop up once more in 'Cold War'. The two Doctors who know them best in a race against time to stop them once more. Could work. Add in the fact they've both battled the Great Intelligence ( 'The Abominable Snowmen','The Web Of Fear','The Snowmen','The Bells Of Saint John' and 'The Name Of The Doctor') and that's two potential avenues to go down. A case could be made for them taking on the Daleks and Cybermen, as both did ad nauseum ( 'The Invasion', 'The Wheel In Space', 'The Power Of The Daleks' and countless others). But wait. There's a massive gap in time between the Macra as massive sentient crabs and dumber devolved beasts as they appeared in 'Gridlock' with the Eleventh's preceding incarnation,so perhaps another adventure involving them is the way forward.