Mission to Magnus
Roots: Various planet of women clichés. Peri learned about Milankovitchian cycles at school.
Goofs: The Doctor claims that he thought the Ice Warriors were extinct, despite knowing that he is in the mid-twenty-third century and having met them thousands of years in the future on Peladon. There is some confusion about orbits and axial tilts.
Technobabble: The Ice Warriors plan to use a bomb with a detonator consisting of an isotope of lithium set in deuterium tritium [this is nonsensical - deuterium and tritium are both isotopes of hydrogen, found in the form of water - aside from anything else, the lithium would disintegrate into the water immediately]. The bombs themselves are neutrino bombs - neutrino-boosted nuclear divisive energy is supposedly a combination of the two most powerful forces in nature.
Continuity: Anzor is the son [sic - cousin? See Lungbarrow] of a former council leader on Gallifrey. He dresses in the style of a Victorian undertaker. He used to bully the Doctor and his classmates when the two of them were in the class of the fourth millennium at school, often using his galvaniser, a blue rod with an orange tip that presumably delivers painful shocks. He used to make the Doctor do his navigational homework. One of the Doctor's classmates, Cheevah, tied to stand up to him; Anzor sealed him in a block of crystal and dropped him into the schoolyard from a great height. Anzor's TARDIS takes on the form of a knarled oak tree when it materialises on Magnus. He met Sil previously on Thoros Beta (see Trial of a Time Lord: Mindwarp). The Doctor soon realises that his childhood fear of Anzor is misplaced. When the Magnusians try to take the formula for time travel from the Doctors mind, he tricks them and gives them the wrong formula, which sends the escaping Anzor on a slow journey to the beginning of time - the Doctor doubts that the rather stupid Anzor will be able to change the settings.
The Ice Warriors intending to invade Magnus only seem to possess a single ship, which is the flagship of a Grand Marshal, who remains on board in orbit. A subordinate, Vedikael, leads the operation on the planet. The Ice Warrior ship destroyed the invasion force from Salvak, but a handful of Salvakians escaped in a recon module and were forced to aid the Martians. The Ice Warriors' armour is impervious to the effects of the Magnusians' force sticks. The Ice Warriors intend to alter the climate of Magnus by detonating bombs at key positions and knocking the planet into an orbit further from its sun. The Doctor manages to reverse this by detonating further bombs. The Ice Warriors are not on the intergalactic business registers.
Sil is now working for his former rivals, Amorb (see Vengeance on Varos). He had formed an alliance with the Ice Warriors to pave the way for their invasion; in return, he intends to profit from the invasion by selling woollen clothing and heating equipment to the conquered Magnusians, once the Martians alter the planets climate.
Trans-replicator mode allows one TARDIS to replace another in space. Only a Gallifreyan Council TARDIS can attract another TARDIS to it against the owners will - this is an emergency facility. Letting non-Time Lords into a TARDIS is forbidden [or possibly just Council TARDISes]. Sil's tampering with the TARDIS controls triggers a time safety jump, which moves it some distance into the future. The TARDIS shows the Magnusians and Sil a future in which the Ice Warriors' plan is successful, and Magnus is freezing, blasted wasteland. Thanks to the Doctor's intervention, this future is avoided [see Pyramids of Mars].
Links: Lord Kiv is mentioned (see Trial of a Time Lord: Mindwarp). The Doctor and Sil briefly discuss Varos and Sil refers to Peri as the Doctor's horrible looking companion (Vengeance on Varos). Vedikael has heard of the Doctor, and notes that he has foiled the Grand Marshal's plans before [this must be a reference to The Seeds of Death, even though the Grand Marshal seen in that story was killed].
Location: Magnus Epsilon, mid-twenty-third century.
Future History: The inhabitants of Magnus Epsilon are descended from human colonists from third Earth. After the colony was established, all the males started to die due to a gender-specific virus present in the atmosphere that reacts to sunlight. The women became dominant, although a few men survive underground and are used for breeding. Males over the age of twenty are culled (put on their sleep list). The planet is ruled by the elected leader of the seven sisterhoods of Magnus. The Palace is located to the North of the planet, near the polar ice cap, the main cities in the South near to the equator. The Rana has a winter palace in the heights of Bassan. Magnus has a blue sky, and there are trees with bright orange flowers. The maternity units, where the young males are kept, are near to the palace, because the nights are shorter there so it is safer for them, since the male-specific virus is activated by sunlight.
Rana Zandusia applies to the High Council of Gallifrey for permission to incorporate Time Travel into their defences, in order to go back in time and stop the largely male population of the neighbouring colony planet Salvak from trying to find an antidote to the virus [It is not made clear how a twenty-third century Earth colony knows about Gallifrey, but the Mentors clearly do, so Sil may have told them in order to further his own plans]. The Magnusians have advanced technology, including memory osmosynthesis, which allows them to enter the brain memory of a subject and pluck information from them [they are apparently quite powerful psychics, despite being human - whether this is an innate ability or a purely technological one is unclear]. Because of this, crime is rare on Magnus, since guilt can always be established. They also manage to pick the locks of Anzor's and the Doctor's TARDISes, by using the Devlin principle of randomized mathematical probability to generate the most likely key combinations.
Salvak is a more arid planet than Epsilon Magnus. Its male rulers manage to find an antidote to the male-specific virus in Magnus's atmosphere. On Salvak, the Amazonian Magnusians are legendary. One of the continents of Salvak is called Avata. Salvakian fauna includes the Woltrop bird.
By the mid-twenty-third century there is a Galactic Lottery, with a ten-year billion credit jackpot.
The Bottom Line: A bit of a mess really. Whilst the return of both Sil and the Ice Warriors is welcome, Anzor is superfluous to the plot and is taken out of the way early on. There is some bad science on display and the ending, in which Ishka more or less decides to marry Rana Zandusia whether she likes it or not, is horribly sexist.