The second multi-Doctor serial to celebrate the franchises 20th Anniversary. Obviously it stars all previous incarnations of the Doctor and some of their companions. However, that's a bit of a lie. Tom Baker is at the start and is quickly brushed out the way, and William Hartnell is replaced by another actor, sadly due to the former's death.
Once again, the anniversary concentrates on the Time Lords, this time revealing Rassilon as the man who made the Time Lords who they are today. I like that these anniversary episodes always choose to deal with the big things. However, once again they feel like a totally different version to what we saw in War Games and The Three Doctors. This truncated watching is makes things very odd. That said, between this and War Games there lies the version we've seen in modern day, so clearly there's a point where their portrayal had a solid base for reinterpretation.
Unlike last time, when the Time Lords were in trouble and needed Five Doctor's to solve the thing, this time the villain gathers the five incarnations together to solve his problem. It's interesting, after all this, it all comes down to internal politics, but the final villain needed a bit more motivation than “I wanna rule for all time” and is probably the weakest thing here. Especially as you have the Master running around then barely plays a part in the final confrontation.
It's also a shame that the Doctors spend so little time with each other. Though even the little bit we get of Two and Three in the same room is awesome, they are mostly kept apart. One and Five are so different its fun seeing him trying to temper his more boisterous companions around his tetchy, younger self.
While I have no real problem with the act of replacing Hartnell, I question giving him such a big role. If it was me I'd have him hang around the background and try and not draw attention to the new actor, especially when you have another Doctor barely in it. Though having looked into this, both seem to be down to Tom Baker refusing to take part. After having agreed to appear, he changed his mind, not wanting to be typecast in a role he'd only left two years previous. So his part was rewritten for Hartnell's replacement, which makes even more sense he's teamed up with Tegan.
Ah yes, the companions. I nearly forgot them. Just like the script seems to. Mostly using them for a bit of exposition. When you have four Doctors to contend with I get the reasoning. The Brigadier, unsurprisingly gets a good showing here, even knocking out the Master. Sarah-Jane on the other hand doesn't at all. Especially when she falls off a 'cliff' that looks like you could walk up no problem. Then the Third Doctor uses a winch to save her, which seems a bit overly dramatic. Susan basically does nothing, though the subtle way all the Doctors react to seeing their grand daughter again was nice, even if it makes me sad no one thought to follow up the fact she's a Time Lady with regenerations. The rest all basically amount to cameos, which is fine, though a little weird for Tegan and Vislor who are the two current companions.
Despite the casting issues, this is actually a good outing for all four of the Doctors involved. If I had to recommend one multi-doctor arc I'd go with The Three Doctors though.