Well, by my count, there are (at least) three different hybrid variations within this specific season (Timelord/Dalek, Ashildr/Mire, and Zygon/Osgood/?? in chronological order)*, without having to refer back to a TV movie that aired before most of the audience were even born.
I liked the Doctor going into his mental TARDIS to work things out - a bit of Sherlock creeping in, Moffatt?
Actually, the mnemonic technique that's often called the Memory Palace (its official name is method of loci (https://en.wikipedia.org/wiki/Method_of_loci)) has been known and used since at least the days of Cicero in ancient Rome. And it makes sense that both Sherlock and the Doctor would use it. Sherlock likely read about it. The Doctor would probably claim he taught Cicero how it works... ;-)
*And maybe Rasmussen/Sandman, depending on how you count.
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I liked the Doctor going into his mental TARDIS to work things out - a bit of Sherlock creeping in, Moffatt?
Actually, the mnemonic technique that's often called the Memory Palace (its official name is method of loci (https://en.wikipedia.org/wiki/Method_of_loci)) has been known and used since at least the days of Cicero in ancient Rome. And it makes sense that both Sherlock and the Doctor would use it. Sherlock likely read about it. The Doctor would probably claim he taught Cicero how it works... ;-)
*And maybe Rasmussen/Sandman, depending on how you count.